This website use cookies and process data.

More information about your rights as a user and the processed data can be found in the privacy policy.

Click on "I Agree", to agree to cookies.
If you do not agree, you can use the website without cookies too.

I Agree

E-mail Header Fields

This list contains over 300 e-mail header fields with their description and additional information.

Abuse-Reports-To

Abuse-Reports-To: abuse@domain.tld

The header field "Abuse-Reports-To" contains the address to which complaints about an e-mail received can be addressed.

(Is not a standard)

Accept-Language

Accept-Language: de, en

The header field "Accept-Language" is the language desired by the sender for replies. It is also possible to specify several languages separated by a comma.

Also-Control

The header field "Also-Control" marks the article as being a control message in addition to being a normal news article and specifies the desired actions.

(Is obsolete, applies to Netnews/Usenet)

Alternate-Recipient

The header field "Alternate-Recipient" controls whether this message can be forwarded to another recipient, e.g. a postmaster, if delivery to the intended recipient is not possible.

Apparently-To

The header field "Apparently-To" is inserted by Sendmail if there are no recipients ("To") in the original message that contain the recipients derived from the SMTP envelope.

Approved

Approved: <moderator@domain.tld>

The header field "Approved" contains the mail addresses and possibly also the names of the moderators who approve the message before it is published. This header is mainly used in moderated news groups and group control messages.

(Applies to Netnews/Usenet)

ARC-Authentication-Results

The header "ARC-Authentication-Results" is part of the Authenticated Received Chain (ARC) protocol. ARC is used to append message authentication information.

ARC-Message-Signature

The header "ARC-Message-Signature" is part of the Authenticated Received Chain (ARC) protocol. ARC is used to append message authentication information.

ARC-Seal

The header "ARC-Seal" is part of the Authenticated Received Chain (ARC) protocol. ARC is used to append message authentication information.

Archive

Archive: yes

The header field "Archive" provides an indication of the poster's intent regarding preservation of the article in publicly accessible long-term or permanent storage.

(Applies to Netnews/Usenet)

Archived-At

Archived-At: <https://www.server.tld/archive/msg/12345>

The header field "Archived-At" contains a URI in angle brackets that refers to the location of the archived message.

(Applies to Mail, applies to Netnews/Usenet)

Article-Names

The header field "Article-Names" contains a reference to specially important articles for a particular Usenet Newsgroup.

(Is obsolete, applies to Netnews/Usenet)

Article-Updates

The header field "Article-Updates" is used to update an article.

(Is obsolete, applies to Netnews/Usenet)

Authentication-Results

Authentication-Results: domain.tld; spf=pass smtp.mailfrom=example.tld

The header field "Authentication-Results" contains the authentication results of a mail server.

Authentication-Results-Original

Authentication-Results-Original: previous.domain.tld; spf=pass smtp.mailfrom=example.tld

The header field "Authentication-Results-Original" contains the authentication results of a previous mail server. When a mail server authenticates a message, it writes the result to the header field "Authentication-Results". If this field already exists, its contents can be saved in the field "Authentication-Results-Original".

(Is not a standard)

Auto-Submitted

Auto-Submitted: auto-replied

The header field "Auto-Submitted" indicates that the message originates from an automatic process or an automatic responder and not from a human. Possible values can be "no", "auto-generated" or "auto-replied", followed by further information.

Autoforwarded

The header field "Autoforwarded" indicates that this massage was automatically forwarded.

Autosubmitted

The header field "Autosubmitted" indicates that this massage was automatically submitted.

Bcc

Bcc: Webmaster <webmaster@domain.tld>

The header field "Bcc" (Blind Carbon Copy) contains additional recipients who should receive the message as "invisible copy". Those additional recipients in the BCC field can not be seen by the other recipients. The recipients in the To and CC field are visible to all recipients.

Cancel-Key

The header field "Cancel-Key" is used to cancel posted messages later.

(Applies to Netnews/Usenet)

Cancel-Lock

The header field "Cancel-Lock" is used to cancel posted messages later.

(Applies to Netnews/Usenet)

Cc

Cc: Name <name@domain.tld>

The header field "Cc" (Carbon Copy) contains additional recipients who should receive the message in "Copy". This information is for administrative purposes only. However, the e-mail is delivered as if the addresses were contained in the To header.

Comments

Comments: Authenticated sender is <name@domain.tld>

The header field "Comments" contains comments of the author or his mail program to the message.

(Applies to Mail, applies to Netnews/Usenet)

Content-Alias

The header field "Content-Alias" is used in addition to "Content-Location" if this content part can be retrieved through more than one URI. Only one of them is allowed in the "Content-Location", the other can be specified in "Content-Alias".

(Is not a standard)

Content-Alternative

The header field "Content-Language" can be attached to a MIME body part to indicate availability of some alternative form of the data it contains. For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Content-Base

Content-Base: https://www.domain.tld/mailcontent/

The header field "Content-Base" contains the absolute base URI for other header fields or HTML tags in this MIME body part that do not have a BASE attribute. For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Content-Class

The header field "Content-Class" contains type information of the content in some class hierarchy. Class hierarchies are commonly used to classify data structures in software development. Also used by Microsoft products and may contain values such as "fax", "call", or "missedcall".

Content-Conversion

Content-Conversion: allowed

The header field "Content-Conversion" indicates whether the text of this message may be converted from one character set to another. Possible values are "prohibited" and "allowed". ("Content-Conversion" equals "Conversion", but is not a standard.)

(Is not a standard)

Content-Description

The header field "Content-Description" contains a description of a particular MIME body part of a message. For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Content-Disposition

Content-Disposition: attachment; filename="invoice.pdf"

The header field "Content-Disposition" indicates whether a MIME body part is to be shown inline or is an attachment. The header field can also indicate a suggested filename for use when saving an attachment to a file. For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Content-Duration

Content-Duration: 25

The header field "Content-Duration" contains the time duration of MIME body part content, in seconds (e.g., for audio or video). For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Content-features

Content-features: (& (Type="image/tiff") (color=Binary) (image-file-structure=TIFF-S) (dpi=200) (dpi-xyratio=200/100) (paper-size=A4) (image-coding=MH) (MRC-mode=0) (ua-media=stationery) )

The header field "Content-features" can be used to annotate a MIME body part with a media feature expression, to indicate features of the body part content. For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Content-ID

The header field "Content-ID" specifies a unique identifier for one MIME body part of a message. For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Content-Identifier

The header field "Content-Identifier" contains a text string that identifies the content of a message.

(Is obsolete)

Content-Language

Content-Language: de-AT, en-US

The header field "Content-Language" includes a code for the natural language used in a MIME body part, e.g. "en" for English. It is also possible to specify several languages separated by a comma. For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Content-Length

Content-Length: 12345

The header field "Content-Length" is inserted by some mail programs to specify the size of the message text in bytes. Using this header field when sending a message can cause problems.

(Is not a standard, Discouraged)

Content-Location

Content-Location: image/123

The header field "Content-Location" specifies an URI that labels the content of a MIME body part in whose heading it is placed. For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message. Example: <img src="image/123"> displays the image from the body part with the header field "Content-Location: image/123".

Content-MD5

The header field "Content-MD5" contains the checksum of the MIME body part content to ensure that it has not been modified. For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Content-Return

The header field "Content-Return" indicates whether the content of a message is to be returned with non-delivery notifications.

(Is obsolete)

Content-SGML-Entity

The header field "Content-SGML-Entity" contains information from the SGML entity declaration corresponding to the entity contained in the body of the body part.

(Is not a standard)

Content-Transfer-Encoding

Content-Transfer-Encoding: quoted-printable

The header field "Content-Transfer-Encoding" specifies how the message text or the MIME body part text is encoded. Usual values are "quoted-printable", "base64", "7bit" and "8bit". For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Content-Type

Content-Type: text/plain; charset=ISO-8859-1

The header field "Content-Type" indicates the type of the message or MIME body part. For example, "text/plain" for text messages or "text/html" for HTML messages are common. "charset" is followed by the character set used. For example, a MIME body part can contain an attachment such as an image or document, or the text or HTML version of the message.

Control

The header field "Control" marks the article as a control message and specifies the desired actions (in addition to the usual actions of storing and/or relaying the article).

(Applies to Netnews/Usenet)

Conversion

Conversion: allowed

The header field "Conversion" indicates whether the text of this message may be converted from one character set to another. Possible values are "prohibited" and "allowed".

Conversion-With-Loss

The header field "Conversion-With-Loss" indicates that the body of this message may not be converted from one character set to another if information will be lost. Possible values are "prohibited" and "allowed".

Date

Date: Wed, 6 Sept 2018 10:02:47 +0000

The header field "Date" contains the creation time or the time of sending. This time is inserted by the sender's mail program. The time is specified in the local time of the sending computer. After the time follows either the deviation to the UTC (e.g. "+0200" for +2 hours), or in some cases also the time zone.

(Applies to Netnews/Usenet)

Date-Received

The header field "Date-Received" records the date and time that the article was first received on the local system. If this header field is present in an article being transmitted from one host to another, the receiving host should ignore it and replace it with the current date.

(Applies to Netnews/Usenet, is obsolete)

Deferred-Delivery

The header field "Deferred-Delivery" provides information about deferred delivery service to the recipient.

Delivered-To

The header field "Delivered-To" is used by some automatic services (mainly MLMs and autoresponders) for the purpose of loop detection. The service adds this header to outgoing messages, with its e-mail address as a value, and discards incoming messages which already have it.

(Is not a standard)

Delivery-Date

The header field "Delivery-Date" contains the time when a message was delivered to its recipient.

Discarded-X400-IPMS-Extensions

The header field "Discarded-X400-IPMS-Extensions" can be used in Internet mail to indicate X.400 IPM extensions that could not be mapped to Internet mail format.

Discarded-X400-MTS-Extensions

The header field "Discarded-X400-MTS-Extensions" can be used in Internet mail to indicate X.400 MTS extensions that could not be mapped to Internet mail format.

Disclose-Recipients

The header field "Disclose-Recipients" indicates whether recipients are to be told the names of other recipients of the same message. This is primarily an X.400 facility. In X.400, this is an envelope attribute and refers to disclosure of the envelope recipient list. Disclosure of other recipients is done in Internet mail via the "To", "Cc" and "Bcc" header fields.

Disposition-Notification-Options

The header field "Disposition-Notification-Options" is used for optional modifiers on disposition notification requests.

Disposition-Notification-To

Disposition-Notification-To: name@domain.tld

The header field "Disposition-Notification-To" contains the mail address to which the read receipt for a message is to be sent.

Distribution

Distribution: de

The header field "Distribution" indicates geographical or organizational limits for the distribution of an article. Common values are "world", "local", "usenet", countries or country codes.

(Applies to Netnews/Usenet)

DKIM-Filter

DKIM-Filter: OpenDKIM Filter v2.11.0 host.domain.tld ABCDEF1234

The header field "DKIM-Filter" contains the product name and version of the DKIM filter, as well as the job ID. DomainKeys Identified Mail (DKIM) is an email authentication method designed to detect forged sender addresses in emails.

DKIM-Signature

DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; s=k1; d=xyz.tld; h= ...

The header field "DKIM-Signature" contains the DKIM signature. DomainKeys Identified Mail (DKIM) is an email authentication method designed to detect forged sender addresses in emails.

DL-Expansion-History

The header field "DL-Expansion-History" contains a trace of distribution lists passed.

DomainKey-Signature

DomainKey-Signature: a=rsa-sha1; c=nofws; q=dns; s=k1; d=xyz.tld; b= ...

The header field "DomainKey-Signature" contains the DomainKey signature. DomainKeys (DK) is an deprecated email authentication method designed to detect forged sender domains in emails.

DomainKey-Status

DomainKey-Status: good (test mode)

The header field "DomainKey-Status" contains the results for domain-based e-mail authentication.

Downgraded-Bcc

The header field "Downgraded-Bcc" contains the original header field ("Bcc") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Cc

The header field "Downgraded-Cc" contains the original header field ("Cc") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Disposition-Notification-To

The header field "Downgraded-Disposition-Notification-To" contains the original header field ("Disposition-Notification-To") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Final-Recipient

The header field "Downgraded-Final-Recipient" contains the original header field ("Final-Recipient") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-From

The header field "Downgraded-From" contains the original header field ("From") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-In-Reply-To

The header field "Downgraded-In-Reply-To" contains the original header field ("In-Reply-To") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Mail-From

The header field "Downgraded-Mail-From" contains the original information from the SMTP envelope ("MAIL FROM") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Message-Id

The header field "Downgraded-Message-Id" contains the original header field ("Message-Id") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Original-Recipient

The header field "Downgraded-Original-Recipient" contains the original header field ("Original-Recipient") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Rcpt-To

The header field "Downgraded-Rcpt-To"" contains the original information from the SMTP envelope ("RCPT TO") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-References

The header field "Downgraded-References" contains the original header field ("References") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Reply-To

The header field "Downgraded-Reply-To" contains the original header field ("Reply-To") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Resent-Bcc

The header field "Downgraded-Resent-Bcc" contains the original header field ("Resent-Bcc") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Resent-Cc

The header field "Downgraded-Resent-Cc" contains the original header field ("Resent-Cc") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Resent-From

The header field "Downgraded-Resent-From" contains the original header field ("Resent-From") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Resent-Message-Id

The header field "Downgraded-Resent-Message-Id" contains the original header field ("Resent-Message-Id") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Resent-Reply-To

The header field "Downgraded-Resent-Reply-To" contains the original header field ("Resent-Reply-To") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Resent-Sender

The header field "Downgraded-Resent-Sender" contains the original header field ("Resent-Sender") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Resent-To

The header field "Downgraded-Resent-To" contains the original header field ("Resent-To") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Return-Path

The header field "Downgraded-Return-Path" contains the original header field ("Return-Path") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-Sender

The header field "Downgraded-Sender" contains the original header field ("Sender") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

Downgraded-To

The header field "Downgraded-To" contains the original header field ("To") if the extension "Email Address Internationalization" (UTF8SMTP) is used, which allows UTF-8 characters in the message header. To allow mail servers that do not support this extension to process the message, the headers must be encoded.

EDIINT-Features

The header field "EDIINT-Features" indicates the originating user agent is capable of supporting the EDIINT features listed. EDIINT stands for Electronic Data Interchange - Internet Integration.

Eesst-Version

Eesst-Version: 1.0

The header field "Eesst-Version" contains the version of the EESST exchange format to which the displayed school transcript conforms. EESST stands for Email Exchange of Secondary School Transcripts.

Encoding

The header field "Encoding" is used in several different ways by different mail systems. Some use it for a kind of content-type information, some for encoding and length information, some for a kind of boundary information, and some in other ways.

Encrypted

The header field "Encrypted" contains message encryption information.

(Is obsolete)

Envelope-To

The header field "Envelope-To" contains the recipients from the SMTP envelope ("RCPT TO") if they are not included in the "To" or "Cc" header fields.

(Is not a standard)

Errors-To

Errors-To: mail@domain.tld

The header field "Errors-To" contains the mail address to which delivery errors are to be sent, such as for a non-existent recipient.

(Is not a standard)

Expires

The header field "Expires" indicates a date and time when the poster deems the article to be no longer relevant and could usefully be removed.

(Applies to Mail, applies to Netnews/Usenet)

Expiry-Date

The header field "Expiry-Date" contains the time at which a message loses its validity. This header field has changed to "Expires".

Fax

The header field "Fax" contains the fax number of the originator.

(Is not a standard)

Fcc

The header field "Fcc" contains the name of file in which a copy of this message is stored.

(Is not a standard)

Feedback-ID

Feedback-ID: ABC:12345:xyz123:senderid

The header field "Feedback-ID" is used by Google and contains information about bulk emails. Bulk email senders can use Feedback Loop (FBL) to identify campaigns that result in high complaint rates among Gmail users. Feedback Loop is especially useful for email service providers to prevent abuse of their services. The FBL data always refers only to recipients with the address "@gmail.com". The content consists of 4 parts separated by a colon. All parts (including the sender ID) are chosen by the sender, but Google recommends the format: Campaign ID:Customer ID:Email type:Sender ID.

(Is not a standard)

Followup-To

The header field "Followup-To" indicates in which newsgroups the poster requested the follow-up. "Followup-To" should only be included if the content differs from "Newsgroups".

(Applies to Netnews/Usenet)

For-Approval

For-Approval: controlling@domain.tld

The header field "For-Approval" contains the primary recipients, who are requested to approve the information in this message or its attachments.

(Is not a standard)

For-Comment

For-Comment: manager@domain.tld

The header field "For-Comment" contains the primary recipients, who are requested to comment on the information in this message or its attachments.

(Is not a standard)

For-Handling

For-Handling: administrator@domain.tld

The header field "For-Handling" contains the primary recipients, who are requested to handle the information in this message or its attachments.

(Is not a standard)

Form-Sub

Form-Sub: v=1 ; ip4=10.1.2.3

The header field "Form-Sub" indicates that the message was sent in response to the submission of a web form. The tags "ip4" or "ip6" contain the IP address from where the web form was sent. Parts of the IP address can be anonymized with "x". If no address can be determined, "ip=none" is inserted.

From

From: Name <name@domain.tld>

The header field "From" contains the mail address and possibly also the name of the sender. This information is inserted by the mail program of the sender.

(Applies to Mail, applies to Netnews/Usenet)

Generate-Delivery-Report

The header field "Generate-Delivery-Report" indicates whether a delivery report is wanted at successful delivery. Default is not to generate such a report.

Importance

Importance: High

The header field "Importance" indicates the importance of the message. The value has no influence on the speed of transmission. This header is used in spam with a high priority value.

In-Reply-To

In-Reply-To: webmaster@domain.tld

The header field "In-Reply-To" contains in case of an answer, the message ID of the answered message for a reply.

Incomplete-Copy

The header field "Incomplete-Copy" indicates that body parts are missing.

Injection-Date

Injection-Date: Sun, 6 Oct 2019 08:04:46 UTC

The header field "Injection-Date" contains the date and time when the article was sent to the network. With this time, news servers can search for outdated articles.

(Applies to Netnews/Usenet)

Injection-Info

The header field "Injection Info" contains information from the sending news server about how an article got into the Netnews system. This helps track the true origin of the article. It can also provide one or more addresses to which complaints can be made about the article's poster.

(Applies to Netnews/Usenet)

IronPort-PHdr

IronPort-PHdr: =?us-ascii?q? Hdhd83K ... hd34Dk3 ?=

The header field "IronPort-PHdr" is inserted by the Graymail engine of Cisco Email Security appliances and contains encoded proprietary information. The data contains information for debugging problems with Graymail configuration and, according to Cisco, cannot be decoded by the customer.

(Is not a standard)

IronPort-SDR

IronPort-SDR: 7jfwH3JKs ... fj4L3==

The header field "IronPort-SDR" is inserted by Cisco Email Security appliances and contains encoded information.

(Is not a standard)

Jabber-ID

Jabber-ID: jabberuser@domain.tld

The header field "Jabber ID" contains the XMPP address of the sender. Special characters in the address are encoded.

(Applies to Mail, applies to Netnews/Usenet)

Keywords

Keywords: Keyword1, Keyword2

The header field "Keywords" contains a comma-separated list of important words and phrases that might be useful for the recipient.

(Applies to Mail, applies to Netnews/Usenet)

Language

Language: en

The header field "Language" includes a code for the natural language used in a message, e.g. "en" for English.

Latest-Delivery-Time

The header field "Latest-Delivery-Time" contains the latest desired delivery time, but will not be acted on by the SMTP infrastructure

Lines

Lines: 23

The header field "Lines" contains the number of line breaks (CRLF) in the message body. "Lines" is deprecated and should be ignored and no longer generated by programs.

(Is obsolete)

List-Archive

List-Archive: <https://www.domain.tld/list/archive/> (Web Archive)

The header field "List-Archive" contains the URL to be used to browse the mailing list archive.

List-Digest

The header field "List-Digest" contains the URL to use to get a subscription to the digest version of the mailing list from which this message was relayed.

(Is not a standard)

List-Help

List-Help: <mailto:newsletter@domain.tld?subject=help> (Help)

The header field "List-Help" contains the URL to use to get information about the mailing list from which this message was relayed.

List-ID

List-Id: "Example Mailing List" <list-example.domain.tld>

The header field "List-ID" stores an identification of the mailing list through which this message was distributed.

List-Owner

List-Owner: <mailto:webmaster@domain.tld> (Contact for Help)

The header field "List-Owner" identifies the path to contact a human administrator for the list. The URL may contain the address of a administrator for the list, the mail system administrator, or any other person who can handle user contact for the list. There is no need to specify "List-Owner" if it is the same person as the mail system administrator (postmaster).

List-Post

List-Post: <mailto:newsletter@domain.tld>

The header field "List-Post" describes the method for posting to the list. This is typically the address of the list, but may be a moderator, or potentially some other form of submission. For the special case of a list that does not allow posting (e.g., an announcements list), the List-Post field may contain the special value "NO".

List-Software

The header field "List-Software" contains information about the software used in a mailing list expander through which this message has passed.

(Is not a standard)

List-Subscribe

List-Subscribe: <http://lists.domain.tld/newsletter>, <mailto:newsletter-request@domain.tld?subject=subscribe>

The header field "List-Unsubscribe" describes the command (preferably using mail) to directly subscribe the user (request addition to the list).

List-Unsubscribe

List-Unsubscribe: <http://lists.domain.tld/newsletter>, <mailto:newsletter-request@domain.tld?subject=unsubscribe>

The header field "List-Unsubscribe" describes the command (preferably using mail) to directly unsubscribe the user (removing them from the list).

List-Unsubscribe-Post

List-Unsubscribe-Post: List-Unsubscribe=One-Click

The header field "List-Unsubscribe-Post" indicates whether an one-click unsubscription from the mailing list is available. A mail receiver can do a one-click unsubscription by performing an HTTPS POST to the HTTPS URI in the "List-Unsubscribe" header field. It sends the key/value pair in the "List-Unsubscribe-Post" header field as the request body.

Mail-Copies-To

The header "Mail-Copies-To" is used in Netnews articles to indicate that followup (=replies) should be sent to the indicated e-mail address.

(Applies to Netnews/Usenet, is not a standard)

Mail-Followup-To

The header field "Mail-Followup-To" contains the addresses that a mail program should use for the "Follow-up" function. Otherwise "Reply-To", "To" and "Cc" are normally used.

(Applies to Netnews/Usenet, is not a standard)

Mail-Reply-Requested-By

Mail-Reply-Requested-By: bounce@domain.tld

The header "Mail-Reply-Requested-By" contains the address to which notifications are to be sent and a request to get delivery notifications.

(Is not a standard)

Mail-Reply-To

The header field "Mail-Reply-To" contains the mail address of the author to whom the reply should be sent. A mail program with the function "Reply to author" should use this address.

(Applies to Netnews/Usenet, is not a standard)

Mail-System-Version

The header file "Mail-System-Version" contains information about the software used to send the message.. Usual information is the name and version number of the software, but also the URL or other information is possible.

(Is not a standard)

Mailer

The header file "Mailer" contains information about the software used to send the message. Usual information is the name and version number of the software, but also the URL or other information is possible.

(Is not a standard)

Message-Context

Message-Context: text-message

The header field "Message-Context" provides information about the context and presentation characteristics of a message. Can have the values "voice-message", "fax-message", "pager-message", "multimedia-message", "text-message" or "none".

Message-ID

Message-ID: <DCEA2913.6003005@domain.tld>

The header field "Message-ID" contains the unique identification of the message. This identifier is generated by the mail program, often from the date. If the Message-ID field is missing, it is usually created and inserted by a mail server.

(Applies to Mail, applies to Netnews/Usenet)

Message-Type

The header field "Message-Type" is only used with the value "Delivery Report" to indicate that this is a delivery report gatewayed from X.400.

MIME-Version

MIME-Version: 1.0

The header field "MIME-Version" contains the version of the Multipurpose Internet Mail Extensions (MIME). The MIME are specifications that concern special characters and multimedia and are used for compatibility when exchanging messages.

MMHS-Acp127-Message-Identifier

The header field "MMHS-Acp127-Message-Identifier" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Authorizing-Users

The header field "MMHS-Authorizing-Users" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Codress-Message-Indicator

The header field "MMHS-Codress-Message-Indicator" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Copy-Precedence

The header field "MMHS-Copy-Precedence" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Exempted-Address

The header field "MMHS-Exempted-Address" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Extended-Authorisation-Info

The header field "MMHS-Extended-Authorisation-Info" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Handling-Instructions

The header field "MMHS-Handling-Instructions" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Message-Instructions

The header field "MMHS-Message-Instructions" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Message-Type

The header field "MMHS-Message-Type" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Originator-PLAD

The header field "MMHS-Originator-PLAD" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Originator-Reference

The header field "MMHS-Originator-Reference" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Other-Recipients-Indicator-CC

The header field "MMHS-Other-Recipients-Indicator-CC" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Other-Recipients-Indicator-To

The header field "MMHS-Other-Recipients-Indicator-To" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Primary-Precedence

The header field "MMHS-Primary-Precedence" is used for message transmission with the Military Message Handling System (MMHS).

MMHS-Subject-Indicator-Codes

The header field "MMHS-Subject-Indicator-Codes" is used for message transmission with the Military Message Handling System (MMHS).

MT-Priority

MT-Priority: 4 (ultra)

The header field "MT-Priority" conveys the priority of the message transfer when a message is forwarded via mail servers that do not support the SMTP extension MT-PRIORITY.

Newsgroups

Newsgroups: alt.binaries

The header field "Newsgroups" contains a list of Usenet newsgroups in which the article was posted. Multiple newsgroups are separated by a comma.

(Applies to Netnews/Usenet)

NNTP-Posting-Date

NNTP-Posting-Date: Sun, 6 Oct 2019 08:04:46 UTC

The header field "NNTP-Posting-Date" contains the date and time when the article was sent to the network. With this time, news servers can search for outdated articles. This header field was replaced by "Injection-Date".

(Applies to Netnews/Usenet, is obsolete)

NNTP-Posting-Host

NNTP-Posting-Host: 10.1.2.3

The header field "NNTP-Posting-Host" is added to the header of a posted article by the server. The contents of the header is either the IP address or the fully qualified domain name of the client host posting the article. This header field was replaced by "Injection-Info".

(Applies to Netnews/Usenet, is obsolete)

Notice-Requested-Upon-Delivery-To

Notice-Requested-Upon-Delivery-To: recipient@domain.tld

The header field "Notice-Requested-Upon-Delivery-To" requests a confirmation when the delivery has been made to the specified recipients.

Obsoletes

Obsoletes: <OLDMSG.35557262@domain.tld>

The header field "Obsoletes" contains the reference to a previous message being corrected and replaced. "Obsoletes" was renamed to "Supersedes".

(Is obsolete)

Organisation

Organisation: Example Company Ltd.

The header field "Organisation" specifies the organization or company name of the sender. The organization can be set in the mail program.

(Is not a standard)

Organization

Organization: Example Company Ltd.

The header field "Organization" specifies the organization or company name of the sender. The organization can be set in the mail program.

(Applies to Mail, applies to Netnews/Usenet)

Original-Encoded-Information-Types

The header field "Original-Encoded-Information-Types" indicates which body part types occur in this message.

Original-From

Original-From: "Sender Name" <name@domain.tld>

The header field "Original-From" contains the original sender ("From") if it is changed by a Sieve script. Sieve is used for simple filtering of mails.

Original-Message-ID

Original-Message-ID: <CFBD8411.8853008@domain.tld>

The header field "Original-Message-ID" contains the original message identifier when the message is resent with alternative content format.

Original-Recipient

Original-Recipient: webmaster@domain.tld

The header field "Original-Recipient" contains the original recipient of the message. The mail server may be able to extract this from the SMTP command RCPT TO. This is used to record the original recipient if the recipient address is changed by a mail server during delivery.

Original-Sender

Original-Sender: sender@domain.tld

The header field "Original-Sender" holds the content of a "Sender" header field in an original message received by an incoming gateway, preserving it while the incoming gateway adds its own Sender header field.

(Applies to Netnews/Usenet)

Original-Subject

Original-Subject: Original example subject

The header field "Original-Subject" contains the original sender ("Subject") if it is changed by a Sieve script. Sieve is used for simple filtering of mails.

Originating-Client

The header file "Originating-Client" contains information about the software used to send the message. Usual information is the name and version number of the software, but also the URL or other information is possible.

(Is not a standard)

Originator

The header field "Originator" is sometimes used in Usenet News in similar ways to "Sender". (The header field "Sender" contains the technical sender, if different from the sender in the "From" field, such as mailing lists.)

(Applies to Netnews/Usenet, is not a standard)

Originator-Info

The header field "Originator-Info" contains information about the authentication of the originator in a format which is not easily used to send email to.

(Applies to Mail, applies to Netnews/Usenet)

Originator-Return-Address

Originator-Return-Address: return@domain.tld

The header field "Originator-Return-Address" contains the return address of the originator.

Path

Path: nntp.server3.tld!news.server2.tld!news.server1.tld!not-for-mail

The header field "Path" indicates the route that an article has taken since its injected into the Usenet. Each server that processes an article is required to prepend at least one entry. This is primarily to ensure that news servers are able to avoid sending an article to already known sites, especially to the sender.

(Applies to Netnews/Usenet)

Phone

The header field "Phone" contains the phone number of the originator.

(Is not a standard)

PICS-Label

The header field "PICS-Label" contains the ratings label to control selection (filtering) of messages according to the PICS protocol. PICS stands for Platform for Internet Content Selection.

Posted-To

Posted-To: alt.binaries

The header field "Posted-To" contains the names of newsgroups to which this message was sent. When a message is sent to both Netnews and email, this header is used in the email version of the message to indicate to which newsgroup it was sent. This header therefore contains the same information as "Newsgroups" in the Netnews version of the message.

(Is not a standard)

Posting-Version

The header field "Posting-Version" identifies the software responsible for entering this message into the network.

(Applies to Netnews/Usenet, is obsolete)

Precedence

Precedence: bulk

The header field "Precedence" is used to indicate the priority that can affect the speed and performance of message transmission. Common values are "bulk" and "first-class". Also used to control automatic replies and stop mailing list loops.

Prevent-NonDelivery-Report

The header field "Prevent-NonDelivery-Report" indicates whether a non-delivery report is wanted on delivery error. Default is to generate such a report.

Priority

Priority: urgent

The header field "Priority" indicates the priority of the message. The value can influence the speed of the message transmission. Possible values are "normal", "urgent" and "non-urgent". Spam messages often use "urgent".

Privicon

Privicon: [X]

The header field "Privicon" contains ASCII characters that indicate how a message should be handled, such as "Do not print" or "Share".

Read-Receipt-To

Read-Receipt-To: sender@domain.tld

The header "Read-Receipt-To" requests an automated confirmation notice when the message is received or read. This header field is ignored by most mail programs.

(Is not a standard)

Received

Received: from sender.tld (sender.tld [10.1.2.3]) by server.tld with SMTP; 4 Oct 2019 15:40:53 +0200

The header field "Received" contains information about the sender, the receiver and the received time of a message. This header is added by the receiving mail server as the top line. Depending on the number of mail servers involved, several "Received" header fields may be included.

Received-SPF

Received-SPF: pass (example.tld: domain of name@domain.tld designates 10.1.2.3 as permitted sender)

The header field "Received-SPF" contains information about the verification of a sender domain via Sender Policy Framework (SPF).

References

References: <DCEA2913.6003005@domain.tld>

The header field "References" contains the message IDs of related messages. In the case of a reply, this would be the message ID of the answered message. This header field is used by mail programs to sort the messages or to display them hierarchically.

(Applies to Mail, applies to Netnews/Usenet)

Registered-Mail-Reply-Requested-By

Registered-Mail-Reply-Requested-By: bounce@domain.tld

The header "Registered-Mail-Reply-Requested-By" contains the address to which notifications are to be sent and a request to get delivery notifications.

(Is not a standard)

Relay-Version

The header field "Relay-Version" shows the version of the program responsible for the transmission of this article over the immediate link, that is, the program that is relaying the article from the next site.

(Applies to Netnews/Usenet, is obsolete)

Replaces

Replaces: <OLDMSG.35557262@domain.tld>

The header field "Replaces" contains the reference to a previous message being corrected and replaced. "Replaces" has the same functionality as "Supersedes".

Reply-By

The header field "Reply-By" contains the latest time by which a reply is requested (not demanded).

Reply-To

Reply-To: mail@domain.tld

The header field "Reply-To" may contain an alternative response address if the response is not to be sent to the From address.

(Applies to Mail, applies to Netnews/Usenet)

Reply-To2

The header field "Reply-To2" is used by some mail systems to indicate a better form of the e-mail address of the sender. Some mailing list expanders puts the name of the list in this header field.

(Is not a standard)

Require-Recipient-Valid-Since

The header field "Require-Recipient-Valid-Since" contains the time when the sender knew the owner of the recipient's mailbox. This can be used to detect changes in mailbox ownership and prevent emails from being delivered to the wrong recipient.

Resent-Bcc

Recent-Cc: bcc-recipient@domain.tld

The header field "Resent-To" contains the mail addresses of the Bcc-recipients to whom the message was resent.

Resent-Cc

Recent-Cc: cc-recipient@domain.tld

The header field "Resent-To" contains the mail addresses of the Cc-recipients to whom the message was resent.

Resent-Date

Date: Wed, 6 Sept 2018 19:46:29 +0000

The header field "Resent-Date" contains the date and time that a message is reintroduced by a user into the message transfer system (forwarded).

Resent-From

Recent-From: from@domain.tld

The header field "Resent-From" contains the address of the person who reintroduced the message into the message transfer system or in whose name the message was resent.

Resent-Message-ID

Message-ID: <DCEA2914.9484449@domain.tld>

The header "Resent-Message-ID" contains the identification of the resent message.

Resent-Reply-To

Resent-Reply-To: reply-to@domain.tld

The header field "Resent-Reply-To" can contain an alternative reply address for the resent message if the reply is not to be sent to the address entered in "Resent-From".

(Is obsolete)

Resent-Sender

Resent-Sender: sender@domain.tld

The header field "Resent-Sender" contains the mail address of the person who has reintroduced the message into the message transfer system, if this differs from "Resent-From".

Resent-To

Resent-To: recipient@domain.tld

The header field "Resent-To" contains the mail addresses of the recipients to whom the message was resent.

Return-Path

Return-Path: name@domain.tld

The "Return-Path" header contains the return address if delivery of the message was not possible. An error message is added to the original email from the mail server that failed to deliver the message. The return path can also be added by a mail server based on the specification under "MAIL FROM".

Return-Receipt-Requested

Return-Receipt-Requested: bounce@domain.tld

The header field "Return-Receipt-Requested" contains an address to which delivery notifications are to be sent.

(Is not a standard)

Return-Receipt-To

Return-Receipt-To: name@domain.tld

The header "Return-Receipt-To" contains the mail-address to which the delivery confirmation is to be sent by the mail server.

(Is not a standard)

See-Also

The header field "See-Also" contains references to other related articles in Netnews.

(Applies to Netnews/Usenet, is obsolete)

Sender

Sender: name@domain.tld

The header field "Sender" contains the technical sender, if different from the sender in the "From" field, such as mailing lists.

(Applies to Mail, applies to Netnews/Usenet)

Sensitivity

Sensitivity: Normal

The header field "Sensitivity" indicates how sensitive it is to forward this message to people other than the specified recipients. Common values are "Personal", "Private", "Company-Confidential", "Internal" and "Normal".

SIO-Label

SIO-Label: marking="EXAMPLE CONFIDENTIAL"; fgcolor=black; bgcolor=red; type=":x411"; label="MQYGASkCAQM="

The header field "SIO-Label" contains information about SIO labels as key/value pairs. A mail client that generates a message can, if configured, offer the user a menu with sensitivities for selection and, when selecting, insert the display markings, foreground and background colors as well as security label parameters associated with this selection into the "SIO-Label" header field of the message.

SIO-Label-History

SIO-Label-History: marking="EXAMPLE CONFIDENTIAL"; fgcolor=black; bgcolor=red; type=":xml"; label*0=" ... "; change=delete; changed-by="delete.example.com"; changed-at="18 Feb 2019 9:24 PDT"; changed-comment="delete"

The header field "SIO-Label-History" contains information on the change history of SIO labels. A mail client that generates a message can, if configured, offer the user a menu with sensitivities for selection and, when selecting, insert the display markings, foreground and background colors as well as security label parameters associated with this selection into the "SIO-Label" header field of the message.

Solicitation

Solicitation: net.example:ADV,org.example:ADV:ADLT

The header field "Solicitation" contains one or more solicitation class keywords.

Speech-Act

The header field "Speech-Act" contains the speech act categorization of a message, examples of speech acts are Question, Idea, More, Promise, Sad, Happy, Angry, Summary, Decision.

(Is not a standard)

Status

The header field "Status" is used by some mail delivery systems to indicate the status of delivery for this message when stored. Common values of this field are: U - message is not downloaded and not deleted, R - message is read or downloaded, O - message is old but not deleted, D - to be deleted, N - new, or a combination of these values.

(Is not a standard)

Subject

Subject: Example subject

The header field "Subject" contains the subject of the message.

(Applies to Mail, applies to Netnews/Usenet)

Summary

Summary: Some examples

The header field "Summary" contains a short phrase summarizing the article's content.

(Applies to Netnews/Usenet)

Supersedes

Supersedes: <OLDMSG.35557262@domain.tld>

The header field "Supersedes" contains the reference to a previous message being corrected and replaced.

(Applies to Mail, applies to Netnews/Usenet)

Telefax

The header field "Telefax" contains the fax number of the originator.

(Is not a standard)

Thread-Index

Thread-Index: AdxySx3+9sgCxf34RIasS7KZ/0zH3Q==

The header field "Thread-Index" is used by Microsoft applications and indicates the relative position of this message within a conversation thread, similar to "References" and "In-reply-To". Mail servers or mail clients from Microsoft (such as Exchange or Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

Thread-Topic

Thread-Topic: Example subject

The header field "Thread-Topic" is used by Microsoft applications and contains the original subject, without any prefixes like "Re:" or "Fwd:". Mail servers or mail clients from Microsoft (such as Exchange or Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

TLS-Report-Domain

TLS-Report-Domain: receiver-domain.tld

The header field "TLS-Report-Domain" contains information about the SMTP TLS Reporting.

TLS-Report-Submitter

TLS-Report-Submitter: sender-domain.tld

The header field "TLS-Report-Submitter" contains information about the SMTP TLS Reporting.

TLS-Required

TLS-Required: No

The header field "TLS-Required" is used for messages for which the originator requests that recipient TLS policy be ignored. This might be done, for example, to report a misconfigured mail server, such as an expired TLS certificate.

To

To: "Webmaster" <webmaster@domain.tld>, name@domain.tld, support@domain.tld (Support Center)

The header field "To" contains one or more recipients. Multiple addresses must be separated by a comma. The order of addresses and names may vary.

Translated-By

The header field "Translated-By" contains the mailbox of the person who made the translation.

(Is not a standard)

Translation-Of

The header field "Translation-Of" contains a reference to the Message-ID of a message, which the current message is a translation of.

(Is not a standard)

User-Agent

User-Agent: ExampleNewsReader 1.0

The header field "User-Agent" contains the name and usually also the version number of the program used for sending the message.

(Applies to Netnews/Usenet)

VBR-Info

VBR-Info: md=somebank.example; mc=transaction; mv=certifier-a.example:certifier-b.example;

The header field "VBR-Info" contains information about the "Vouch By Reference" (VBR) protocol used to add third-party certifications to mails.

X-...

Header fields beginning with "X-" are usually not standardized. They are used by applications such as spam filters, anti-virus software, mail servers, and mail clients to add information to a message.

(Is not a standard)

X-Accept-Language

X-Accept-Language: de, en

The header field "X-Accept-Language" indicates the languages accepted by the sender. Answers to this message should be written in one of these languages.

(Is not a standard)

X-Account-Key

X-Account-Key: account1

The header field "X-Account-Key" is added by Mozilla Thunderbird to indicate the internal name of the account with which the message was received.

(Is not a standard)

X-Admin

X-Admin: admin@domain.tld

The header field "X-Admin" contains the e-mail address of administrator of a server, through which this message was submitted.

(Is not a standard)

X-Amp-File-Uploaded

X-Amp-File-Uploaded: False

The header field "X-Amp-File-Uploaded" is inserted by Cisco Email Security Appliances and contains information from the Advanced Malware feature.

(Is not a standard)

X-Amp-Original-Verdict

X-Amp-Original-Verdict: FILE UNKNOWN

The header field "X-Amp-Original-Verdict" is inserted by Cisco Email Security Appliances and contains information from the Advanced Malware feature. Possible values are "File unknown" and "Verdict unknown".

(Is not a standard)

X-Amp-Result

X-Amp-Result: Clean

The header field "X-Amp-Result" is inserted by Cisco Email Security Appliances and contains the result of malware detection.

(Is not a standard)

X-AntiAbuse

X-AntiAbuse: Sender Address Domain - domain.tld

The header field "X-AntiAbuse" contains information for tracking abuse (spam, phishing, fraud, etc.).

(Is not a standard)

X-antispameurope-...

Header fields beginning with "X-antispameurope-" are inserted by a spam filter from Hornetsecurity GmbH (formerly antispameurope GmbH).

(Is not a standard)

X-Antivirus

X-Antivirus: AV-Software 1.2.3 (VirDef: 18.10.2019), Outbound message

The header field "X-Antivirus" usually contains the name and the version number of the anti-virus software, as well as possibly further information, such as the date of the virus definitions.

(Is not a standard)

X-Antivirus-Status

X-Antivirus-Status: Clean

The header field "X-Antivirus-Status" is used to note the result of a virus scan.

(Is not a standard)

X-Apparently-To

The header field "X-Apparently-To" is an alternative to "Apparently-To", which is inserted by Sendmail if there are no recipients ("To") in the original message that contain the recipients derived from the SMTP envelope.

(Is not a standard)

X-Archived-At

X-Archived-At: <https://www.server.tld/archive/msg/12345>

The header field "X-Archived-At" contains a URI in angle brackets that refers to the location of the archived message. This header is a precursor of "Archived-At" and should no longer be used.

(Applies to Mail, applies to Netnews/Usenet)

X-AttachmentOrder

The header field "X-AttachmentOrder" is used by Microsoft mail clients and contains a list of file names for the audio file attachments that are to be played as part of a message. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-Auto-Response-Suppress

X-Auto-Response-Suppress: All

The header field "X-Auto-Response-Suppress" is used by Microsoft mail clients and specifies whether a client or server application will forego sending automated replies in response to this message. The value can be "None" or "All". Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-CallID

The header field "X-CallID" is used by Microsoft mail clients and contains a unique identifier associated with the phone call. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-CallingTelephoneNumber

The header field "X-CallingTelephoneNumber" is used by Microsoft mail clients and contains the telephone number of the caller associated with a voice mail message. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-Complaints-To

X-Complaints-To: abuse@domain.tld

The header field "X-Complaints-To" contains the address to which complaints about an e-mail received can be addressed.

(Is not a standard)

X-Confirm-Reading-To

X-Confirm-Reading-To: sender@domain.tld

The header "X-Confirm-Reading-To" requests an automated confirmation notice when the message is received or read. This header field is ignored by most mail programs.

(Is not a standard)

X-CrossPremisesHeaders...

Header fields beginning with "X-CrossPremisesHeaders" are typically inserted by Microsoft Exchange when a message is sent from the on-premises environment to Exchange Online.

(Is not a standard)

X-CrossPremisesHeadersFilteredBySendConnector

X-CrossPremisesHeadersFilteredBySendConnector: host.domain.tld

The header field "X-CrossPremisesHeadersFilteredBySendConnector" is used by Microsoft Exchange. For a message sent from the on-premises environment to Exchange Online, this header field contains the Edge Transport Server oon which the cross-premises headers were filtered.

(Is not a standard)

X-Distribution

X-Distribution: bulk

The header field "X-Distribution" with the value "bulk" is used by Pegasus Mail when sending a message with many recipients. This is intended to detect and filter spam messages sent with Pegasus Mail.

(Is not a standard)

X-Env-From

X-Env-From: noname@example.tld

The header field "X-Env-From" is used by some mail servers to enter the address given in the SMTP dialog ("MAIL FROM").

(Is not a standard)

X-Env-Sender

X-Env-Sender: noname@example.tld

The header field "X-Env-Sender" is used by some mail servers to enter the address given in the SMTP dialog ("MAIL FROM").

(Is not a standard)

X-Envelope-From

X-Envelope-From: name@domain.tld

The header field "X-Envelope-From" contains the sender from the SMTP envelope ("MAIL FROM") if it is not the same as the senders in the "From" or "Sender" header fields.

(Is not a standard)

X-Envelope-Sender

X-Envelope-Sender: noname@example.tld

The header field "X-Envelope-Sender" is used by some mail servers to enter the address given in the SMTP dialog ("MAIL FROM").

(Is not a standard)

X-Envelope-To

X-Envelope-To: webmaster@domain.tld

The header field "X-Envelope-To" contains the recipients from the SMTP envelope ("RCPT TO") if they are not included in the "To" or "Cc" header fields.

(Is not a standard)

X-EOPTenantAttributedMessage

X-EOPTenantAttributedMessage: 42df9e9f-e7f6-20af-b827-e4651f674820

The header "X-EOPTenantAttributedMessage" is used by Microsoft Office 365 and contains a GUID which represents a unique Office 365 tenant.

(Is not a standard)

X-Errors-To

X-Errors-To: name@domain.tld

The header field "Errors-To" contains the mail address to which delivery errors are to be sent, such as for a non-existent recipient.

(Is not a standard)

X-Face

The header field "X-Face" contains a 48x48 bitmap picture of the sender of this message.

(Is not a standard)

X-FaxNumberOfPages

The header field "X-FaxNumberOfPages" is used by Microsoft mail clients and contains the number of pages in a Fax object. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-Forefront-...

Header fields beginning with "X-Forefront-" are inserted by a Microsoft Forefront application (spam filter and anti-virus software).

(Is not a standard)

X-Forefront-Antispam-Report

X-Forefront-Antispam-Report: x-forefront-antispam-report: CIP:10.1.2.3;SFV:SKI;SFS:;DIR:INB;SFP:;SCL:-1;SRVR:PR3PR01MB8636;H:PR3PR08MB8377.eurprd02.prod.outlook.com;FPR:;SPF:None;LANG:de;

The header "X-Forefront-Antispam-Report" is used by Microsoft Office 365 and contains information about spam protection. This information may include, but is not limited to, the IP connection address ("CIP:"), the spam rating ("SCL:"), the phishing rating ("PCL:") or the language used in the message ("LANG").

(Is not a standard)

X-GMX-Antispam

X-GMX-Antispam: -2 (not scanned, spam filter disabled)

The header field "X-GMX-Antispam" is inserted by GMX mail servers and contains information about the spam protection of GMX.

(Is not a standard)

X-GMX-Antivirus

X-GMX-Antivirus: -1 (not scanned, may not use virus scanner)

The header field "X-GMX-Antivirus" is inserted by GMX mail servers and contains information about the virus protection of GMX.

(Is not a standard)

X-GMX-HTML

X-GMX-HTML: 1 

The header field "X-GMX-HTML" is inserted by GMX mail servers.

(Is not a standard)

X-GMX-UID

X-GMX-UID: f9Htf ... 1N12+

The header field "X-GMX-UID" is inserted by GMX mail servers.

(Is not a standard)

X-Google-DKIM-Signature

X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=domain.tld; s=20191025; h=x-gm-message-state:message-id:date:subject:from:to:mime-version:content-transfer-encoding; bh=joset8yp ... HxQ==

The header field "X-Google-DKIM-Signature" contains the DKIM signature of messages, sent via Google mail servers (e.g. GMail). DomainKeys Identified Mail (DKIM) is an email authentication method designed to detect forged sender addresses in emails.

(Is not a standard)

X-Greylist

X-Greylist: delayed 555 seconds by postgrey-1.34 at servername; Fri, 04 Oct 2019 12:51:48 CEST

The header field "X-Greylist" contains information about the greylisting of a message. This is a method of fighting spam in which the message is not accepted by an unknown sender until a new delivery attempt is made.

(Is not a standard)

X-IMAP

The header field "X-IMAP" contains the UID, as defined in the IMAP standard. Only used in internal mailbox storage in some mail systems, should never be visible to a user.

(Is not a standard)

X-imss-scan-details

The header field "X-imss-scan-details" is used by Trend Micro products and contains the results for all spam or phishing filters, in the sequence by which the rules were applied.

(Is not a standard)

X-IronPort-...

Header fields beginning with "X-IronPort-" are inserted by Cisco Email Security appliances.

(Is not a standard)

X-IronPort-Anti-Spam-Filtered

X-IronPort-Anti-Spam-Filtered: true

The header field "X-IronPort-Anti-Spam-Filtered" is inserted by Cisco Email Security appliances and indicates whether the message was checked for spam.

(Is not a standard)

X-Ironport-Anti-Spam-Filtered

X-Ironport-Anti-Spam-Filtered: True

The header field "X-Ironport-Anti-Spam-Filtered" is inserted by Cisco Email Security Appliances and contains the indication (True or False) whether a message has been filtered for spam.

(Is not a standard)

X-IronPort-Anti-Spam-Result

X-IronPort-Anti-Spam-Result: =?us-ascii?q?Hd4kd ... Kd74J34f?=

The header field "X-IronPort-Anti-Spam-Result" is inserted by Cisco Email Security appliances and contains encoded information.

(Is not a standard)

X-Ironport-Anti-Spam-Result

X-Ironport-Anti-Spam-Result: A7Bf948 ... 16A23BEQA

The header field "X-Ironport-Anti-Spam-Result" is inserted by Cisco Email Security Appliances and contains the hashed result of the spam filtering.

(Is not a standard)

X-Ironport-AV

X-Ironport-Av: E=Sophos;i="5.11,510,1737454500"; d="scan'201,229";a="854730900"

The header field "X-Ironport-AV" is inserted by Cisco Email Security Appliances and contains the encoded details pertaining to anti-virus scanning.

(Is not a standard)

X-IronPort-Outbreak-Description

The header field "X-IronPort-Outbreak-Description" is inserted by Cisco Email Security Appliances and contains information from the Virus Outbreak Filtering feature.

(Is not a standard)

X-IronPort-Outbreak-Status

The header field "X-IronPort-Outbreak-Status" is inserted by Cisco Email Security Appliances and contains information from the Virus Outbreak Filtering feature.

(Is not a standard)

X-KLMS-AntiPhishing

The header field "X-KLMS-AntiPhishing" is inserted by Kaspersky Security for Linux Mail Server into messages processed by the Anti-Phishing module.

(Is not a standard)

X-KLMS-AntiSpam-Auth

The header field "X-KLMS-AntiSpam-Auth" is added by Kaspersky Security for Linux Mail Server and contains information about the authenticity of the message sender.

(Is not a standard)

X-KLMS-AntiSpam-Envelope-From

X-KLMS-AntiSpam-Envelope-From: name@domain.tld

The header field "X-KLMS-AntiSpam-Envelope-From" is added by Kaspersky Security for Linux Mail Server and contains the message sender.

(Is not a standard)

X-KLMS-AntiSpam-Info

X-KLMS-AntiSpam-Info: {FROM: no valid address in FROM, no dot}, {DNS response errors}

The header field "X-KLMS-AntiSpam-Info" is added by Kaspersky Security for Linux Mail Server and contains the criteria used by the Anti-Spam module to assign the status to the message.

(Is not a standard)

X-KLMS-AntiSpam-Interceptor-Info

X-KLMS-AntiSpam-Interceptor-Info: scan successful

The header field "X-KLMS-AntiSpam-Interceptor-Info" is added by Kaspersky Security for Linux Mail Server and contains the result of the message scan. Possible values are: "protection disabled" if the Anti-Spam module is disabled. "timeout expired" if the message was queued for scanning, but has not been scanned due to timeout exceeded. "size exceeded" if the message was not queued for scanning due to its large size. "scan successfull" if the message successfully scanned und "fallback" if the message was queued for scanning, but has not been scanned due to an error.

(Is not a standard)

X-KLMS-AntiSpam-Lua-Profiles

X-KLMS-AntiSpam-Lua-Profiles: 35793 [Aug 20 2012]

The header field "X-KLMS-AntiSpam-Lua-Profiles" is added by Kaspersky Security for Linux Mail Server.

(Is not a standard)

X-KLMS-AntiSpam-Method

X-KLMS-AntiSpam-Method: none 

The header field "X-KLMS-AntiSpam-Method" is added by Kaspersky Security for Linux Mail Server and contains the successfully used spam recognition method.

(Is not a standard)

X-KLMS-AntiSpam-Moebius-Timestamps

X-KLMS-AntiSpam-Moebius-Timestamps: 1971238, 1971643, 1971629

The header field "X-KLMS-AntiSpam-Moebius-Timestamps" is added by Kaspersky Security for Linux Mail Server.

(Is not a standard)

X-KLMS-AntiSpam-Rate

X-KLMS-AntiSpam-Rate: 20

The header field "X-KLMS-AntiSpam-Rate" is added by Kaspersky Security for Linux Mail Server and contains the rating assigned to the message by the Anti-Spam module.

(Is not a standard)

X-KLMS-AntiSpam-Spf

X-KLMS-AntiSpam-Spf: pass

The header field "X-KLMS-AntiSpam-Spf" is added by Kaspersky Security for Linux Mail Server and contains information about checking a sender domain using Sender Policy Framework (SPF).

(Is not a standard)

X-KLMS-AntiSpam-Version

X-KLMS-AntiSpam-Version: 5.2.1

The header field "X-KLMS-AntiSpam-Version" is added by Kaspersky Security for Linux Mail Server and contains the Anti-Spam module version.

(Is not a standard)

X-KLMS-AntiVirus

X-KLMS-AntiVirus: Kaspersky Linux Mail Security 8.0.0.359, bases: 2012/08/20 04:12:00 #7814976

The header field "X-KLMS-Antivirus" is added by Kaspersky Security for Linux Mail Server and contains info about the application (version, release date and number of antivirus signatures).

(Is not a standard)

X-KLMS-AntiVirus-Status

X-KLMS-AntiVirus-Status: Clean, skipped

The header field "X-KLMS-AntiSpam-Status" is added by Kaspersky Security for Linux Mail Server and contains the status assigned to the message by the Anti-Spam module after scanning.

(Is not a standard)

X-KLMS-Message-Action

X-KLMS-Message-Action: skipped, ContentFiltering

The header field "X-KLMS-Message-Action" is added by Kaspersky Security for Linux Mail Server and contains the action applied by the application to the message, and modules used in its scanning.

(Is not a standard)

X-KLMS-Rule-ID

X-KLMS-Rule-ID: 4

The header field "X-KLMS-Rule-ID" is added by Kaspersky Security for Linux Mail Server and contains a list of IDs of the rules used in scanning the message.

(Is not a standard)

X-List-Host

The header field "X-List-Host" contains information about the software used in a mailing list expander through which this message has passed.

(Is not a standard)

X-Listserver

The header field "X-Listserver" contains information about the software used in a mailing list expander through which this message has passed.

(Is not a standard)

X-Loop

The header field "X-Loop" is used by some automatic services (mainly MLMs and autoresponders) for the purpose of loop detection. The service adds this header to outgoing messages, with its e-mail address as a value, and discards incoming messages which already have it.

(Is not a standard)

X-Mailer

X-Mailer: ExampleMailer 1.23

The header file "X-Mailer" contains information about the software used to send the message. Usual information is the name and version number of the software, but also the URL or other information is possible.

(Is not a standard)

X-Message-Flag

The header field "X-Message-Flag" is used by Microsoft mail clients and can contain a custom text. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-Microsoft-...

Header fields beginning with "X-Microsoft-" are usually inserted by a Microsoft application.

(Is not a standard)

X-Microsoft-Antispam

X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:(7020095) ... (1701031045);SRVR:DB9EUR03HT123;

The header "X-Microsoft-Antispam" is used by Microsoft Office 365 and contains information on spam protection, such as the phishing rating ("PCL:").

(Is not a standard)

X-Microsoft-Antispam-...

Header fields beginning with "X-Microsoft-Antispam-" are usually inserted by Microsoft Exchange Online (Office 365) and contain information on spam and phishing protection.

(Is not a standard)

X-Microsoft-ClassDesc

The header field "X-Microsoft-ClassDesc" is used by Microsoft mail clients and contains a human-readable summary of each of the classification categories included in the header field "X-Microsoft-Classification". Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-Microsoft-ClassID

The header field "X-Microsoft-ClassID" is used by Microsoft mail clients and contains the GUID that identifies the list of email classification categories used by a Message object. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-Microsoft-Classification

The header field "X-Microsoft-Classification" is used by Microsoft mail clients and contains a list of the classification categories to which this Message object has been assigned. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-Microsoft-Classified

X-Microsoft-Classified: true

The header field "X-Microsoft-Classified" is used by Microsoft mail clients and indicates whether the contents of a message are regarded as classified information. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-Microsoft-ClassKeep

X-Microsoft-ClassKeep: true

The header field "X-Microsoft-ClassKeep" is used by Microsoft mail clients and indicates whether the message uses any classification categories. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-MIME-Autoconverted

The header field "X-MIME-Autoconverted" contains information about conversion of this message on the path from sender to recipient, like conversion between MIME encoding formats. Note: Auto-conversion may invalidate digital seals and signatures.

(Is not a standard)

X-MimeOLE

X-MimeOLE: Produced By Microsoft MimeOLE V16.4.3528.331

The header field "X-MimeOLE" contains information about the Microsoft MimeOLE version.

(Is not a standard)

X-Mittente

The header field "X-Mittente" is used when sending messages with "La Posta Elettronica Certificata" (Italian Certified Electronic Mail).

X-Mozilla-Keys

X-Mozilla-Keys: $label1 MyTag

The header field "X-Mozilla-Keys" is used by Mozilla Thunderbird to store the tags assigned to the message by the user.

(Is not a standard)

X-Mozilla-Status

X-Mozilla-Status: 0005

The header field "X-Mozilla-Status" is used by Mozilla Thunderbird to store the message status or properties of a message. For example, whether a message has been read or marked.

(Is not a standard)

X-Mozilla-Status2

X-Mozilla-Status2: 00000000

The header field "X-Mozilla-Status2" is inserted by Mozilla Thunderbird.

(Is not a standard)

X-MS-...

Header fields beginning with "X-MS-" are usually inserted by a Microsoft application.

(Is not a standard)

X-MS-Exchange-...

Header fields beginning with "X-MS-Exchange-" are usually inserted by a Microsoft Exchange Server or Exchange Online (Office 365).

(Is not a standard)

X-MS-Exchange-CrossTenant-FromEntityHeader

X-MS-Exchange-CrossTenant-FromEntityHeader: Internet

The header "X-MS-Exchange-CrossTenant-FromEntityHeader" is used by Microsoft Office 365.

(Is not a standard)

X-MS-Exchange-CrossTenant-Id

X-MS-Exchange-CrossTenant-Id: 42df9e9f-e7f6-20af-b827-e4651f674820

The header "X-MS-Exchange-CrossTenant-Id" is used by Microsoft Office 365 and often represents the GUID of the tenant which sent the message, but won't always, depending on how the mail routed through Exchange Online and if there were hops to third party devices as a message moved from one tenant to another.

(Is not a standard)

X-MS-Exchange-CrossTenant-MailboxType

X-MS-Exchange-CrossTenant-MailboxType: HOSTED

The header "X-MS-Exchange-CrossTenant-MailboxType" is used by Microsoft Office 365.

(Is not a standard)

X-MS-Exchange-CrossTenant-Network-Message-Id

X-MS-Exchange-CrossTenant-Network-Message-Id: 77f3c78b-32f0-40a9-4a52-02d94620b777

The header "X-MS-Exchange-CrossTenant-Network-Message-Id" is used by Microsoft Office 365.

(Is not a standard)

X-MS-Exchange-CrossTenant-OriginalArrivalTime

X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Oct 2019 19:43:25.8461 (UTC)

The header "X-MS-Exchange-CrossTenant-OriginalArrivalTime" is used by Microsoft Office 365 and probably contains the original arrival time of the message.

(Is not a standard)

X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp

X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=42df9e9f-e7f6-20af-b827-e4651f674820;Ip=[10.1.2.3];Helo=[host.name.domain.tld]

The header "X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp" is used by Microsoft Office 365.

(Is not a standard)

X-MS-Exchange-Organization-AuthAs

X-MS-Exchange-Organization-AuthAs: Anonymous

The header "X-MS-Exchange-Organization-AuthAs" is used by Microsoft Office 365.

(Is not a standard)

X-MS-Exchange-Organization-AuthSource

X-MS-Exchange-Organization-AuthSource: ME7AUS01FT080.eop-AUS07.prod.protection.outlook.com

The header "X-MS-Exchange-Organization-AuthSource" is used by Microsoft Office 365.

(Is not a standard)

X-MS-Exchange-Organization-AutoForwarded

X-MS-Exchange-Organization-AutoForwarded: true

The header field "X-MS-Exchange-Organization-AutoForwarded" is used by Microsoft mail clients and indicates that this message has been automatically generated or automatically forwarded. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-MS-Exchange-Organization-AVStamp-Mailbox

X-MS-Exchange-Organization-AVStamp-Mailbox: AV-Software;1;0;info

The header "X-MS-Exchange-Organization-AVStamp-Mailbox" is used by Microsoft Office 365 and usually contains the name of the anti-virus software used, as well as any other information.

(Is not a standard)

X-MS-Exchange-Organization-PCL

X-MS-Exchange-Organization-PCL: 2

The header field "X-MS-Exchange-Organization-SCL" is used by Microsoft Exchange Server and specifies the phishing probability of the message. A value from 1 to 3 is probably not phishing, a value from 4 to 8 is probably phishing.

(Is not a standard)

X-MS-Exchange-Organization-PRD

The header field "X-MS-Exchange-Organization-PRD" is used by Microsoft Exchange Server and contains the domain name of the last sender responsible for transmitting the current message. PRD stands for Purported Sender Domain. Mail servers or mail clients from Microsoft (such as Exchange or Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-MS-Exchange-Organization-SCL

The header field "X-MS-Exchange-Organization-SCL" is used by Microsoft Exchange Server and specifies the spam probability or trust level of the message. The value -1 indicates that the message originates from a trusted sender and is never treated as spam. The values 0 (low) to 9 (high) indicate the spam probability calculated from the message content. SCL stands for Spam Confidence Level. Mail servers or mail clients from Microsoft (such as Exchange or Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-MS-Exchange-Organization-SenderIdResult

The header field "X-MS-Exchange-Organization-SenderIdResult" is used by Microsoft applications and reports the results of a Sender-ID check. Mail servers or mail clients from Microsoft (such as Exchange or Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-MS-Exchange-Transport-CrossTenantHeadersStamped

X-MS-Exchange-Transport-CrossTenantHeadersStamped: ME4PR07MB0012

The header "X-MS-Exchange-Transport-CrossTenantHeadersStamped" is used by Microsoft Exchange.

(Is not a standard)

X-MS-Exchange-Transport-EndToEndLatency

X-MS-Exchange-Transport-EndToEndLatency: 00:00:01.4742304

The header "X-MS-Exchange-CrossTenant-Id" is used by Microsoft Exchange.

(Is not a standard)

X-MS-Has-Attach

X-MS-Has-Attach: Yes

The header field "X-MS-Has-Attach" is used by Microsoft applications and specifies that the message contains attachments if the value is "Yes". Mail servers or mail clients from Microsoft (such as Exchange or Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-MS-Office365-...

Header fields beginning with "X-MS-Office365-" are usually inserted by Microsoft Office 365.

(Is not a standard)

X-MS-TNEF-Correlator

X-MS-TNEF-Correlator: <225 ... 855@....EURP732.PROD.OUTLOOK.COM>

The header field "X-MS-TNEF-Correlator" is created by Microsoft applications when creating a new TNEF message and contains the Message-ID of the parent message. TNEF stands for Transport Neutral Encapsulation Format. Mail servers or mail clients from Microsoft (such as Exchange or Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-MSMail-Priority

X-MSMail-Priority: Normal

The header field "X-MSMail-Priority" is used by Microsoft mail programs to specify the priority of the message. The value has no influence on the speed of transmission. This header is used in spam with a high priority value.

(Is not a standard)

X-Newsreader

X-Newsreader: ExampleNewsReader 1.23

The header file "X-Newsreader" contains information about the software used to send the message. Usual information is the name and version number of the software, but also the URL or other information is possible.

(Applies to Mail, applies to Netnews/Usenet, is not a standard)

X-No-Archive

X-No-Archive: Yes 

The header field "X-No-Archive" indicates that the message should not be included in a public archive.

(Is not a standard)

X-Original-To

X-Original-To: webmaster@domain.tld

The header field "X-Original-To" contains the original recipient of the message.

X-OriginalArrivalTime

The header field "X-OriginalArrivalTime" contains the time when this message was delivered into the message transport system (usually the same time as in the last "Received" header field).

(Is not a standard)

X-Originating-IP

X-Originating-IP: 10.1.2.3

The header field "X-Originating-IP" contains the IP address of the client when using the HTTP frontend of a mail service (Web-Mail). Since the HTTP frontend is the client for the SMTP server the IP of the HTTP frontend is recorded in the "Received" header field. The header field "X-Originating-IP" is used to identify the client of the HTTP frontend.

(Is not a standard)

X-Payload-Class

The header field "X-Payload-Class" is used by Microsoft mail clients and contains the class name of an object that can display the contents of the message. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-Payload-Provider-GUID

The header field "X-Payload-Provider-GUID" is used by Microsoft mail clients and contains the GUID of the software application that can display the contents of the message. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-PGP-Sig

X-PGP-Sig: 2.6.2 Subject,Control,Message-ID,Date,From,Sender iQCVAw ... srA=

The header field "X-PGP-Sig" starts with the PGP version number from the signed output, then has the signed headers separated by commas (no spaces), and finally has the signature.

(Applies to Netnews/Usenet)

X-Phalanx-Mark

X-Phalanx-Mark: SPAM

The header field "X-Phalanx-Mark" is inserted by the Phalanx Spam-Filter and contains the classification of the message as "SPAM" or "HAM".

X-Phalanx-Rules

X-Phalanx-Rules: 3 rules matched: RULE_OFFER, HTML_IMG_LINK, BAYES

The header field "X-Phalanx-Rules" is inserted by the Phalanx Spam-Filter and contains the matched rules.

X-Phalanx-Score

X-Phalanx-Score: 305

The header field "X-Phalanx-Rules" is inserted by the Phalanx Spam-Filter and contains the message score. A value above 50 is more likely to be spam than non-spam.

X-PMFLAGS

The header field "X-PMFLAGS" is inserted by Pegasus Mail into sent messages.

X-Priority

X-Priority: 3 (Normal)

The header field "X-Priority" indicates the priority of the message. The value has no influence on the speed of transmission. Possible values are: 1 (Very high), 2 (High), 3 (Normal), 4 (Low), 5 (Very low). Sometimes only the number is used. This header is used in spam with a high priority value.

X-RCPT-TO

The header field "Envelope-To" contains the recipients from the SMTP envelope ("RCPT TO").

(Is not a standard)

X-Received

from sender.tld (sender.tld [10.1.2.3]) by server.tld with SMTP; 4 Oct 2019 15:40:53 +0200

The header field "X-Received" contains information about the sender, the receiver and the received time of a message. This header is added by the receiving mail server as the top line. This header field is mostly used in internal networks.

(Is not a standard)

X-Report-Abuse

X-Report-Abuse: abuse@domain.tld

The header field "X-Report-Abuse" contains the address to which complaints about an e-mail received can be addressed.

(Is not a standard)

X-Report-Abuse-To

X-Report-Abuse-To: abuse@domain.tld

The header field "X-Report-Abuse-To" contains the address to which complaints about an e-mail received can be addressed.

(Is not a standard)

X-Ricevuta

The header field "X-Ricevuta" is used when sending messages with "La Posta Elettronica Certificata" (Italian Certified Electronic Mail).

X-Riferimento-Message-ID

The header field "X-Riferimento-Message-ID" is used when sending messages with "La Posta Elettronica Certificata" (Italian Certified Electronic Mail).

X-Sender

X-Sender: noname@example.tld

The header field "X-Sender" is used by some mail servers to enter the address given in the SMTP dialog ("MAIL FROM"). The POP or IMAP account name, to which no message can be sent, may also be entered by some mail servers.

X-Sensitivity

X-Sensitivity: 3

The header field "X-Sensitivity" indicates how sensitive it is to forward this message to people other than the specified recipients. Common values are "Personal", "Private", "Company-Confidential", "Internal" and "Normal". However, a number can also be specified as a value.

(Is not a standard)

X-Spam

X-Spam: Yes

The header field "X-Spam" is used by spam filters to specify the status of the message and/or the result of the filtering.

(Is not a standard)

X-Spam-...

Header fields beginning with "X-Spam-" are usually inserted by spam filters.

(Is not a standard)

X-Spam-Checker-Version

X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on domain.tld

The header field "X-Spam-Checker-Version" is inserted by Apache SpamAssassin and contains, besides the program name, also the version number. There may be more information about how the release date or hostname was executed on SpamAssassin.

(Is not a standard)

X-Spam-Flag

X-Spam-Flag: NO

The header field "X-Spam-Flag" contains the result of a spam check. The value is normally either "YES" (spam) or "NO" (no spam).

(Is not a standard)

X-Spam-Level

X-Spam-Level: ***

The header field "X-Spam-Level" is inserted by Apache SpamAssassin. The number of asterisks ("*") corresponds to the integer part of the message score. If plus signs ("+") are added, they represent the number of tenths of the score value. For example, the characters "*******++" correspond to the score 5.2.

(Is not a standard)

X-Spam-Report

X-Spam-Report: 15.50/6.0 * -0.1 -- Forwarded email (Outlook style) *  0.9 -- From: ends in numbers ...

The header field "X-Spam-Report" is inserted by Apache SpamAssassin and contains the result of the spam check. It starts with the score value of the message, followed by the score limit. Then follow the applicable rules and their respective scores.

(Is not a standard)

X-Spam-Score

X-Spam-Score: -0.619

The header field "X-Spam-Score" is inserted by Apache SpamAssassin and specifies the score value of the message. The higher this value, the more likely the message is to be spam. The score value can also be negative.

(Is not a standard)

X-TipoRicevuta

The header field "X-TipoRicevuta" is used when sending messages with "La Posta Elettronica Certificata" (Italian Certified Electronic Mail).

X-TM-...

Header fields beginning with "X-TM-" are usually inserted by Trend Micro products.

(Is not a standard)

X-TM-AS-Product-Ver

X-TM-AS-Product-Ver: IMSS-7.1.0.1224-8.2.0.1013-24980.000

The header field "X-TM-AS-Product-Ver" is used by Trend Micro products and contains, separated by hyphens, the product name, product version, anti-spam engine version, and virus definition (spam pattern) version.

(Is not a standard)

X-TM-AS-Result

X-TM-AS-Result: No-1.618200-5.000000-10

The header field "X-TM-AS-Result" is used by Trend Micro products and contains, separated by hyphens, the spam classification ("Yes" or "NO"), the score value (Trend Score), the spam detection threshold, the category and the type (Trend Type).

(Is not a standard)

X-TM-AS-Result-Xfilter

X-TM-AS-Result-Xfilter: Match text exemption rules:No

The header field "X-TM-AS-Result-Xfilter" is used by Trend Micro products and contains information for checking the text exception rules (X-Filter Check). If a message match a defined regular expression, it is not classified as spam.

(Is not a standard)

X-TM-AS-SMTP

X-TM-AS-SMTP: 1.0 aG9zdC5kb21haW4udGxk c2VuZGVyQGRvbWFpbi50bGQ

The header field "X-TM-AS-SMTP" is used by Trend Micro products and contains the HELO and MAIL FROM information from the SMTP envelope received by the gateway filter. Both are separated by a space and each is Base64 encoded.

(Is not a standard)

X-TM-AS-User-Approved-Sender

X-TM-AS-User-Approved-Sender: Yes

The header field "X-TM-AS-User-Approved-Sender" is used by Trend Micro products and contains the result ("Yes" or "No") of the verification with the list of approved senders. If the sender matches an address in the approved senders list, the message will not be classified as spam.

(Is not a standard)

X-TM-AS-user-Blocked-Sender

X-TM-AS-user-Blocked-Sender: No

The header field "X-TM-AS-user-Blocked-Sender" is used by Trend Micro products and contains the result ("Yes" or "No") of the verification with the list of blocked senders. If the sender matches an address in the blocked senders list, the message will be classified as spam.

(Is not a standard)

X-TM-Authentication-Results

X-TM-Authentication-Results: spf=pass (sender IP address: 10.1.2.3) smtp.mailfrom=domain.tld;

The header field "X-TM-Authentication-Results" is used by Trend Micro products and contains the authentication results of a Sender Policy Framework (SPF) or DomainKeys Identified Mail (DKIM) verification.

(Is not a standard)

X-TM-Deliver-Signature

The header field "X-TM-Deliver-Signature" is used by Trend Micro products and contains an MD5 hash value generated from the sender and message ID.

(Is not a standard)

X-TMASE-MatchedRID

X-TMASE-MatchedRID: hGed94JSd ... dj/d8LR4d

The header field "X-TMASE-Version" is used by Trend Micro Anti-Spam Engine (TMASE) and contains vendor proprietary debug information.

(Is not a standard)

X-TMASE-Result

X-TMASE-Result: 10--16.285300-8.000000

The header field "X-TMASE-Version" is used by Trend Micro Anti-Spam Engine (TMASE) and usually contains in most cases, separated by hyphens, the type (Trend Type), the score value (Trend Score) and the spam detection threshold.

(Is not a standard)

X-TMASE-SNAP-Result

X-TMASE-SNAP-Result: 1.486001.0001-0-1-16:0,44:0,22:0,12:1,39:0,32:0,35:0,50:0-0

The header field "X-TMASE-Version" is used by Trend Micro Anti-Spam Engine (TMASE) Social Engineering Attack Protection (SNAP) and contains the result of the check. Separated by hyphens, it also contains the version number, the scan result and the aggressiveness level of the check.

(Is not a standard)

X-TMASE-Version

X-TMASE-Version: SMEX-12.5.0.2039-8.5.1020-24982.005

The header field "X-TMASE-Version" is used by Trend Micro Anti-Spam Engine (TMASE) and contains in most cases, separated by hyphens, the product name, product version, anti-spam engine version, and virus definition (spam pattern) version.

(Is not a standard)

X-Trasporto

The header field "X-Trasporto" is used when sending messages with "La Posta Elettronica Certificata" (Italian Certified Electronic Mail).

X-UI-Application

X-UI-Application: 4:xtdresult=NTUw ... MTsw,xtdcapabilities

The header field "X-UI-Application" is inserted by mail servers of United Internet (GMX, Web.de, 1&1 and some more).

(Is not a standard)

X-UI-Filterresults

X-UI-Filterresults: notjunk:1;V03:K0:IAYZrhZLGH8=:Chj9OR ... GL8iF2bz=

The header field "X-UI-Filterresults" is inserted by mail servers of United Internet (GMX, Web.de, 1&1 and some more) and contains the results of the spam filtering.

(Is not a standard)

X-UI-Out-Filterresults

X-UI-Out-Filterresults: notjunk:1;V01:K0:CFCUBW ... 1gFe6

The header field "X-UI-Out-Filterresults" is inserted by mail servers of United Internet (GMX, Web.de, 1&1 and some more) and contains the results of the spam filtering.

(Is not a standard)

X-UI-Sender-Class

X-UI-Sender-Class: b1640dde-48d7-17be-28f0-84072f62da06

The header field "X-UI-Application" is inserted by mail servers of United Internet (GMX, Web.de, 1&1 and some more).

(Is not a standard)

X-UIDL

X-UIDL: 0003419c47ba0615

The header field "X-UIDL" contains the unique identifier of the message for the mail server. It is used for receiving messages via the Post Office Protocol (POP). In this way, the mail program avoids, for example, reloading a message that has already been downloaded.

X-URI

The header field "X-URI" is sometimes used with the same meaning as "Content-Location", sometimes to indicate the web home page of the sender or of his organization.

(Is not a standard)

X-URL

The header field "X-URL" is sometimes used with the same meaning as "Content-Location", sometimes to indicate the web home page of the sender or of his organization.

(Is not a standard)

X-VerificaSicurezza

The header field "X-VerificaSicurezza" is used when sending messages with "La Posta Elettronica Certificata" (Italian Certified Electronic Mail).

X-Virus-Checked

X-Virus-Checked: Checked

The header field "X-Virus-Checked" is used to indicate that a virus scan has been performed.

(Is not a standard)

X-Virus-Scanned

X-Virus-Scanned: amavisd-new at localdomain

The header field "X-Virus-Scanned" contains information about a virus scan. In most cases, the name of the software and the name of the checking host are specified. However, sometimes only the result, like "OK", is noted.

(Is not a standard)

X-Virus-Status

X-Virus-Status: Clean

The header field "X-Virus-Status" is used to note the result of a virus scan. Sometimes the name of the anti-virus software is also noted.

(Is not a standard)

X-VirusChecked

X-VirusChecked: Checked

The header field "X-VirusChecked" is used to indicate that a virus scan has been performed.

(Is not a standard)

X-VoiceMessageDuration

The header field "X-VoiceMessageDuration" is used by Microsoft mail clients and specifies the length of the attached audio message, in seconds. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-VoiceMessageSenderName

The header field "X-VoiceMessageSenderName" is used by Microsoft mail clients and specifies the name of the caller who left the attached voice message, as provided by the voice network's caller ID system. Mail clients from Microsoft (such as Outlook) use this header field when converting Message objects used by Microsoft products to MIME messages.

(Is not a standard)

X-X-Sender

The header field "X-X-Sender" is used by some mail servers to indicate an authentication of the sender which might not be usable to send e-mail to.

(Is not a standard)

X400-Content-Identifier

The header field "X400-Content-Identifier" contains a text string that identifies the content of a message.

X400-Content-Return

The header field "X400-Content-Return" indicates whether the content of a message is to be returned with non-delivery notifications.

X400-Content-Type

The header field "X400-Content-Type" contains the X400 content type.

X400-MTS-Identifier

The header field "X400-MTS-Identifier" contains the X400 MTS-Identifier.

X400-Originator

The header field "X400-Originator" contains the X400 Originator.

X400-Received

The header field "X400-Received" contains the X400 Received.

X400-Recipients

The header field "X400-Recipients" contains the X400 Recipients.

X400-Trace

The header field "X400-Trace" contains the X400 Trace.

Xref

The header field "Xref" indicates where an article from the last news server was filed for editing. User agents often use the information in the Xref header to prevent the user from seeing the same article twice if it was sent to more than one newsgroup. This header field is also used by Microsoft applications and contains the name of the host and a white-space-separated list of colon-separated pairs of newsgroup names and message numbers.

(Applies to Netnews/Usenet)

Did you like my page, one of my freeware applications or online tools?

With my PayPal.Me link you can support the publishing of this free content with any amount you want quickly and easily.

Read more about support options...