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.
2.1.8. Header Field: Message-ID
Description:
Message identifier
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.4)
Related information:
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.
2.1.9. Header Field: In-Reply-To
Description:
Identify replied-to message(s)
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.4)
Related information:
The message identifier(s) of the original message(s) to which the
current message is a reply. Defined as standard by RFC 822.
2.1.10. Header Field: References
Description:
Related message identifier(s)
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.4)
Related information:
The message identifier(s) of other message(s) to which the current
message may be related. In RFC 2822, 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.
2.1.11. Header Field: Subject
Description:
Topic of message
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.5)
Related information:
Contains a short string identifying the topic of the message.
Defined as standard by RFC 822.
2.1.12. Header Field: Comments
Description:
Additional comments about the message
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.5)
Related information:
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.
2.1.13. Header Field: Keywords
Description:
Message key words and/or phrases
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.5)
Related information:
Contains a comma-separated list of important words and phrases
that might be useful for the recipient. Defined as standard by
RFC 822.
2.1.14. Header Field: Resent-Date
Description:
Date and time message is resent
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.6)
Related information:
Contains the date and time that a message is reintroduced into the
message transfer system. Defined as standard by RFC 822.
2.1.15. Header Field: Resent-From
Description:
Mailbox of person for whom message is resent
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.6)
Related information:
Contains the mailbox of the agent who has reintroduced the message
into the message transfer system, or on whose behalf the message
has been resent. Defined as standard by RFC 822.
2.1.16. Header Field: Resent-Sender
Description:
Mailbox of person who actually resends the message
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.6)
Related information:
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.
2.1.17. Header Field: Resent-To
Description:
Mailbox to which message is resent
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.6)
Related information:
Contains the mailbox(es) to which the message has been resent.
Defined as standard by RFC 822.
2.1.18. Header Field: Resent-Cc
Description:
Mailbox(es) to which message is cc’ed on resend
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.6)
Related information:
Contains the mailbox(es) to which message is cc’ed on resend.
Defined as standard by RFC 822.
2.1.19. Header Field: Resent-Bcc
Description:
Mailbox(es) to which message is bcc’ed on resend
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.6)
Related information:
Contains the mailbox(es) to which message is bcc’ed on resend.
Defined as standard by RFC 822.
2.1.20. Header Field: Resent-Reply-To
Description:
Resent reply-to
Applicable protocol: Mail [18]
Status: obsolete
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18]
Related information:
Resent Reply-to. Defined by RFC 822, obsoleted by RFC 2822.
2.1.21. Header Field: Resent-Message-ID
Description:
Message identifier for resent message
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.6)
Related information:
Contains a message identifier for a resent message. Defined as
standard by RFC 822.
2.1.22. Header Field: Return-Path
Description:
Message return path
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.7)
Related information:
Return path for message response diagnostics. See also RFC 2821
[17]. Defined as standard by RFC 822.
2.1.23. Header Field: Received
Description:
Mail transfer trace information
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2822 [18] (section 3.6.7)
Related information:
Contains information about receipt of the current message by a
mail transfer agent on the transfer path. See also RFC 2821 [17].
Defined as standard by RFC 822.
2.1.24. Header Field: Encrypted
Description:
Message encryption information
Applicable protocol: Mail [18]
Status: obsolete
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 822 [2]
Related information:
Defined by RFC 822, but was found to be inadequately specified,
was not widely implemented, and was 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.
2.1.25. Header Field: Disposition-Notification-To
Description:
Mailbox for sending disposition notification
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2298 [12]
Related information:
Indicates that the sender wants a disposition notification when
this message is received (read, processed, etc.) by its
recipients.
2.1.26. Header Field: Disposition-Notification-Options
Description:
Disposition notification options
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2298 [12]
Related information:
For optional modifiers on disposition notification requests.
2.1.27. Header Field: Accept-Language
Description:
Language(s) for auto-responses
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 3282 [21]
Related information:
Indicates a language that the message sender requests to be used
for responses. Accept-language was not designed for email but has
been considered 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; and determining what character set encoding
should be used.
2.1.28. Header Field: Original-Message-ID
Description:
Original message identifier
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 3297 [22]
Related information:
Original message identifier used with resend of message with
alternative content format; identifies the original message data
to which it corresponds.
2.1.29. Header Field: PICS-Label
Description:
PICS rating label
Applicable protocol: Mail [18]
Status: standard
Author/change controller:
W3C (mailto:web-human@w3.org)
World Wide Web Consortium
Specification document(s):
PICS-labels [24]
Related information:
Ratings label to control selection (filtering) of messages
according to the PICS protocol. Specified for general use with
RFC 822 message format, with HTTP-specific extensions.
2.1.30. Header Field: Encoding
Description:
Message encoding and other information
Applicable protocol: Mail [18]
Status: experimental
Author/change controller:
Albert K. Costanzo (mailto:AL@AKC.COM)
AKC Consulting Inc.
Specification document(s):
RFC 1505 [4]
Related information:
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.
2.1.31. Header Field: List-Archive
Description:
URL of mailing list archive
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2369 [13]
Related information:
Contains the URL to use to browse the archives of the mailing list
from which this message was relayed.
2.1.32. Header Field: List-Help
Description:
URL for mailing list information
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2369 [13]
Related information:
Contains the URL to use to get information about the mailing list
from which this message was relayed.
2.1.33. Header Field: List-ID
Description:
Mailing list identifier
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2919 [20]
Related information:
Stores an identification of the mailing list through which this
message was distributed.
2.1.34. Header Field: List-Owner
Description:
URL for mailing list owner’s mailbox
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2369 [13]
Related information:
Contains the URL to send e-mail to the owner of the mailing list
from which this message was relayed.
2.1.35. Header Field: List-Post
Description:
URL for mailing list posting
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2369 [13]
Related information:
Contains the URL to use to send contributions to the mailing list
from which this message was relayed.
2.1.36. Header Field: List-Subscribe
Description:
URL for mailing list subscription
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2369 [13]
Related information:
Contains the URL to use to get a subscription to the mailing list
from which this message was relayed.
2.1.37. Header Field: List-Unsubscribe
Description:
URL for mailing list unsubscription
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2369 [13]
Related information:
Contains the URL to use to unsubscribe the mailing list from which
this message was relayed.
2.1.38. Header Field: Message-Context
Description:
Type or context of message
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 3458 [23]
Related information:
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’.
2.1.39. Header Field: DL-Expansion-History
Description:
Trace of distribution lists passed
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
Trace of distribution lists passed. (MIXER X.400 mapping; not for
general use.)
2.1.40. Header Field: Alternate-Recipient
Description:
Controls forwarding to alternate recipients
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
Controls whether this message may be forwarded to an alternate
recipient, such as a postmaster, if delivery to the intended
recipient is not possible. Default: Allowed. RFC 2156 (MIXER),
not for general use.
2.1.41. Header Field: Original-Encoded-Information-Types
Description:
Body part types in message
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
Which body part types occur in this message. RFC 2156 (MIXER);
not for general use.
2.1.42. Header Field: Content-Return
Description:
Return content on non-delivery?
Applicable protocol: Mail [18]
Status: obsolete
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 1327 [3]
Related information:
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.
2.1.43. Header Field: Generate-Delivery-Report
Description:
Request delivery report generation
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
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.
2.1.44. Header Field: Prevent-NonDelivery-Report
Description:
Non-delivery report required?
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
Indicates whether a non-delivery report is wanted on delivery
error. Default is to generate such a report. RFC 2156 (MIXER);
not for general use.
2.1.45. Header Field: Obsoletes
Description:
Reference message to be replaced
Applicable protocol: Mail [18]
Status: obsolete
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 1327 [3]
Related information:
Reference to a previous message being corrected and replaced.
Compare to ’Supersedes:’,f used in Usenet News. Introduced by RFC
1327 and subsequently renamed by RFC 2156 to ’Supersedes’.
2.1.46. Header Field: Supersedes
Description:
Reference message to be replaced
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
Reference to a previous message being corrected and replaced.
Renamed version of obsolete ’Obsoletes’ header field. RFC 2156
(MIXER); not for general use.
2.1.47. Header Field: Content-Identifier
Description:
Message content identifier
Applicable protocol: Mail [18]
Status: obsolete
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 1327 [3]
Related information:
A text string that identifies the content of a message.
Introduced by RFC 1327 and subsequently changed by RFC 2156 to
avoid confusion with MIME defined fields. Gateways that reverse
map may support the old field.
2.1.48. Header Field: Delivery-Date
Description:
Message delivery time
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
The time when a message was delivered to its recipient. RFC 2156
(MIXER); not for general use.
2.1.49. Header Field: Expiry-Date
Description:
Message expiry time
Applicable protocol: Mail [18]
Status: obsolete
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 1327 [3]
Related information:
Time at which a message loses its validity. Introduced by RFC
1327 and subsequently changed by RFC 2156 to ’Expires:’.
2.1.50. Header Field: Expires
Description:
Message expiry time
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
Time at which a message loses its validity. Renamed version of
obsolete Expiry-Date header field. RFC 2156 (MIXER), not for
general use.
2.1.51. Header Field: Reply-By
Description:
Time by which a reply is requested
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
Latest time by which a reply is requested (not demanded). RFC
2156 (MIXER); not for general use.
2.1.52. Header Field: Importance
Description:
Message importance
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
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) [10]
and RFC 3801 (VPIM) [14].
2.1.53. Header Field: Incomplete-Copy
Description:
Body parts are missing
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]
Related information:
Body parts are missing. RFC 2156 (MIXER); not for general use.
2.1.54. Header Field: Priority
Description:
Message priority
Applicable protocol: Mail [18]
Status: standards-track
Author/change controller:
IETF (mailto:iesg@ietf.org)
Internet Engineering Task Force
Specification document(s):
RFC 2156 [10]