Message date and time Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.1) Specifies the date and time at which the creator of the message indicated that the message was complete and ready to enter the mail delivery system. Defined as standard by RFC 822.

Mailbox of message author Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.2) Specifies the author(s) of the message, that is, the mailbox(es) of the person(s) or system(s) responsible for the writing of the message. Defined as standard by RFC 822.

Mailbox of message sender Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.2) Specifies the mailbox of the agent responsible for the actual transmission of the message. Defined as standard by RFC 822.

Mailbox for replies to message Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.2) When the "Reply-To:" field is present, it indicates the mailbox(es) to which the author of the message suggests that replies be sent. Defined as standard by RFC 822.

Primary recipient mailbox Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.3) Contains the address(es) of the primary recipient(s) of the message. Defined as standard by RFC 822.

Carbon-copy recipient mailbox Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.3) Contains the addresses of others who are to receive the message, though the content of the message may not be directed at them. Defined as standard by RFC 822.

Blind-carbon-copy recipient mailbox Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.3) Contains addresses of recipients of the message whose addresses are not to be revealed to other recipients of the message. Defined as standard by RFC 822.

Message identifier Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.4) Contains a single unique message identifier that refers to a particular version of a particular message. If the message is resent without changes, the original Message-ID is retained. Defined as standard by RFC 822.

Identify replied-to message(s) Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.4) The message identifier(s) of the original message(s) to which the current message is a reply. Defined as standard by RFC 822.

Related message identifier(s) Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.4) The message identifier(s) of other message(s) to which the current message may be related. In RFC2822, the definition was changed to say that this header field contains a list of all Message-IDs of messages in the preceding reply chain. Defined as standard by RFC 822.

Topic of message Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.5) Contains a short string identifying the topic of the message. Defined as standard by RFC 822.

Additional comments about the message Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.5) Contains any additional comments on the text of the body of the message. Warning: Some mailers will not show this field to recipients. Defined as standard by RFC 822.

Message key words and/or phrases Mail standards IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.5) Contains a comma-separated list of important words and phrases that might be useful for the recipient. Defined as standard by RFC 822.

Date and time message is resent Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.6) Contains the date and time that a message is reintroduced into the message transfer system. Defined as standard by RFC 822.

Mailbox of person for whom message is resent Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.6) Contains the mailbox of the agent who has reintroduced the message into the message transfer system, or on whose behanlf the message has been resent. Defined as standard by RFC 822.

Mailbox of person who actually resends the message Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.6) Contains the mailbox of the agent who has reintroduced the message into the message transfer system, if this is different from the Resent-From value. Defined as standard by RFC 822.

Mailbox to which message is resent Mail standards IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.6) Contains the mailbox(es) to which the message has been resent. Defined as standard by RFC 822.

Mailbox(es) to which message is cc'ed on resend Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.6) Containes the mailbox(es) to which message is cc'ed on resend. Defined as standard by RFC 822.

Mailbox(es) to which message is bcc'ed on resend Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.6) Containes the mailbox(es) to which message is bcc'ed on resend. Defined as standard by RFC 822.

Resent reply-to Mail obsolete IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 Resent Reply-to. Defined by RFC 822, obsoleteed by RFC2822.

Message identifier for resent message Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.6) Contains a message identifier for a resent message. Defined as standard by RFC 822.

Message return path Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.7) Return path for message response diagnostics. See also, RFC 2821. Defined as standard by RFC 822.

Mail transfer trace information Mail standard IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2822 (section 3.6.7) Contains information about receipt of the current message by a mail transfer agent on the transfer path. See also, RFC 2821. Defined as standard by RFC 822.

Message encryption information Mail obsolete IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 822 Defined by RFC 822, but was found to be inadequately specified, not widely implemented, and removed in RFC 2822. Current practice is to use separate encryption, such as S/MIME or OpenPGP, possibly in conjunction with RFC 1847 MIME security multiparts.

Mailbox for sending disposition notification Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2298 Indicates that the sender wants a disposition notification when this message is received (read, processed, etc.) by its recipients.

Disposition notification options Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2298 For optional modifiers on disposition notification requests.

Language(s) for auto-responses Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 3282 Indicates a language that the message sender requests be used for responses. Accept-language was not designed for email, but has been considered to be useful as input to the generation of automatic replies. Some problems have been noted concerning its use with email, including but not limited to: determination of the email address to which it refers; cost and lack of effective internationalization of email responses; interpretation of language subtags; determining what character set encoding should be used.

Original message identifier Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 3297 Original message identifier used with resend of message with alternative content format, identifies the original message data to which it corresponds.

PICS rating label Mail standard W3C (mailto:web-human@w3.org) World Wide Web Consortium PICS-labels Ratings label to control selection (filtering) of messages according to the PICS protocol. Specified for general use with RFC822 message format, with HTTP-specific extensions

Message encoding and other information Mail experimental Albert K. Costanzo (mailto:AL@AKC.COM) AKC Consulting Inc. RFC 1505 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, some in other ways.

URL of mailing list archive Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2369 Contains URL to use to browse the archives of the mailing list from which this message was relayed.

URL for mailing list information Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2369 Contains URL to use to get a information about the mailing list from which this message was relayed.

Mailing list identifier Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2919 Stores an identification of the mailing list, through which this message was distributed.

URL for mailing list owner's mailbox Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2369 Contains URL to send e-mail to the owner of the mailing list from which this message was relayed.

URL for mailing list posting Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2369 Contains URL to use to send contributions to the mailing list from which this message was relayed.

URL for mailing list subscription Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2369 Contains URL to use to get a subscription to the mailing list from which this message was relayed.

URL for mailing list unsubscription Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2369 Contains URL to use to unsubscribe the mailing list from which this message was relayed.

Type or context of message Mail Standards track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC3458 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', 'none'.

Trace of distribution lists passed Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Trace of distribution lists passed. (MIXER X.400 mapping, not for general use.)

Controls forwarding to alternate recipients Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Controls whether this message may be forwarded to alternate recipients such as a postmaster if delivery is not possible to the intended recipient. Default: Allowed. RFC 2156 (MIXER), not for general use.

Body part types in message Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Which body part types occur in this message. RFC 2156 (MIXER), not for general use.

Return content on non-delivery? Mail obsolete IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 1327 Indicates whether the content of a message is to be returned with non-delivery notifications. Introduced by RFC 1327, and subsequently changed by RFC 2156 to avoid confusion with MIME defined fields.

Request delivery report generation Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Indicates whether a delivery report is wanted at successful delivery. Default is not to generate such a report. RFC 2156 (MIXER), not for general use.

Non-delivery report required? Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Indicates whether non-delivery report is wanted on delivery error. Default is to generate such a report. RFC 2156 (MIXER), not for general use.

Reference message to be replaced Mail obsolete IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 1327 Reference to a previous message being corrected and replaced. Compare to 'Supersedes:' used in Usenet News. Introduced by RFC 1327, and subsequently renamed by RFC 2156 to 'Supersedes'.

Reference message to be replaced Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Reference to a previous message being corrected and replaced. Renamed version of obsolete 'Obsoletes' header field. RFC 2156 (MIXER), not for general use.

Message content identifier Mail obsolete IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 1327 A text string which identifies the content of a message. Introduced by RFC 1327, and subsequently changed by RFC 2156 to avoid confusion with MIME defined fields. Gateways which reverse map may support the old field.

Message delivery time Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 The time when a message was delivered to its recipient. RFC 2156 (MIXER), not for general use.

Message expiry time Mail obsolete IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 1327 Time at which a message loses its validity. Introduced by RFC 1327, and subsequently changed by RFC 2156 to 'Expires:'.

Message expiry time Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Time at which a message loses its validity. Renamed version of obsolete Expiry-Date header field. RFC 2156 (MIXER), not for general use.

Time by which a reply is requested Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Latest time at which a reply is requested (not demanded). RFC 2156 (MIXER), not for general use.

Message importance Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 A hint from the originator to the recipients about how important a message is. Values: High, normal or low. Not used to control transmission speed. Proposed for use with RFC 2156 (MIXER) and RFC 2421 (VPIM).

Body parts are missing. Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Body parts are missing. RFC 2156 (MIXER), not for general use.

Message priority Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Can be 'normal', 'urgent' or 'non-urgent' and can influence transmission speed and delivery. RFC 2156 (MIXER), not for general use.

Message content sensitivity Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 How sensitive it is to disclose this message to other people than the specified recipients. Values: Personal, private, company confidential. The absence of this header field in messages gatewayed from X.400 indicates that the message is not sensitive. Proposed for use with RFC 2156 (MIXER) and RFC 2421 (VPIM).

X.400 message content lenguage Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Can include a code for the natural language used in a message, e.g. 'en' for English. See also 'Content-Language'. RFC 2156 (MIXER), not for general use.

Conversion allowed? Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 The body of this message may not be converted from one character set to another. Values: Prohibited and allowed. RFC 2156 (MIXER), not for general use.

Lossy conversion allowed? Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 The body of this message may not be converted from one character set to another if information will be lost. Values: Prohibited and allowed. RFC 2156 (MIXER), not for general use.

Message type: delivery report? Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Only used with the value 'Delivery Report' to indicates that this is a delivery report gatewayed from X.400. RFC 2156 (MIXER), not for general use.

Automatically submitted indicator Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Has been automatically submitted. RFC 2156 (MIXER), not for general use.

Automatically forwarded indicator Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Has been automatically forwarded. RFC 2156 (MIXER), not for general use.

X.400 IPM extensions discarded Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Can be used in Internet mail to indicate X.400 IPM extensions which could not be mapped to Internet mail format. RFC 2156 (MIXER), not for general use.

X.400 MTS extensions discarded Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Can be used in Internet mail to indicate X.400 MTS extensions which could not be mapped to Internet mail format. RFC 2156 (MIXER), not for general use.

Disclose names of other recipients? Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Tells 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 in Internet mail done via the To:, cc: and bcc: header fields. Not for general use.

Deferred delivery information Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Provides information about deferred delivery service to the recipient. RFC 2156 (MIXER), not for general use.

Latest delivery time requested Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Provides the recipient information about requested delivery, but will not be acted on by the SMTP infrastrucuture. RFC 2156 (MIXER), not for general use.

Originator return address Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Originator return address. RFC 2156 (MIXER), not for general use.

Message content identifier Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 A text string which identifies the content of a message. Renamed version of obsolete Content-Identifier field. RFC 2156 (MIXER), not for general use.

Return content on non-delivery? Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 Indicates whether the content of a message is to be returned with non-delivery notifications. Renamed version of obsolete Content-Return field. RFC 2156 (MIXER), not for general use.

X400 content type Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 X400 content type. RFC 2156 (MIXER), not for general use.

X400 MTS-Identifier Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 X400 MTS-Identifier. RFC 2156 (MIXER), not for general use.

X400 Originator Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 X400 Originator. RFC 2156 (MIXER), not for general use.

X400 Received Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 X400 Received. RFC 2156 (MIXER), not for general use.

X400 Recipients Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 X400 Recipients. RFC 2156 (MIXER), not for general use.

X400 Trace Mail standards-track IETF (mailto:iesg@ietf.org) Internet Engineering Task Force RFC 2156 X400 Trace. RFC 2156 (MIXER), not for general use.