reports/rfc/draft-ietf-mailext-mail-attributes-04.txt

   1 Network Working Group                                       Jacob Palme
   2 Internet Draft                                 Stockholm University/KTH
   3 draft-ietf-mailext-mail-attributes-04.txt                        Sweden
   4 Category: Informational                                        May 1996
   5 Expires November 1996
   6
   7
   8
   9
  10
  11                   Common Internet Message Headers
  12
  13                         Status of this Memo
  14
  15
  16
  17   This document is an Internet-Draft.  Internet-Drafts are working
  18   documents of the Internet Engineering Task Force (IETF), its
  19   areas, and its working groups.  Note that other groups may also
  20   distribute working documents as Internet-Drafts.
  21
  22   Internet-Drafts are draft documents valid for a maximum of six
  23   months and may be updated, replaced, or obsoleted by other
  24   documents at any time.  It is inappropriate to use Internet-
  25   Drafts as reference material or to cite them other than as
  26   ``work in progress.''
  27
  28   To learn the current status of any Internet-Draft, please check
  29   the ``1id-abstracts.txt'' listing contained in the Internet-
  30   Drafts Shadow Directories on ftp.is.co.za (Africa),
  31   nic.nordu.net (Europe), munnari.oz.au (Pacific Rim),
  32   ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast).
  33
  34   This memo provides information for the Internet community. This'
  35   memo does not specify an Internet standard of any kind, since
  36   this document is mainly a compilation of information taken from
  37   other RFCs.. Distribution of this memo is unlimited.
  38
  39
  40
  41                             Abstract
  42
  43 This memo contains a table of commonly occurring headers in headings of
  44 e-mail messages. The document compiles information from other RFCs such
  45 as RFC 822, RFC 1036, RFC 1123, RFC 1327, RFC 1496, RFC 1521, RFC 1766,
  46 RFC 1806 and RFC 1864. A few commonly occurring headers which are not
  47 defined in RFCs are also included. For each header, the memo gives a
  48 short description and a reference to the RFC in which the header is
  49 defined.
  50
  51
  52
  53
  54
  55
  56
  57 Palme                                                           [Page 1]
  58 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
  59
  60
  61                          Table of contents
  62
  63 1. Introduction
  64
  65 2. Use of gatewaying headers
  66
  67 3. Table of headers
  68
  69    3.1 Phrases used in the tables
  70    3.2 Trace information
  71    3.3 Format and control information
  72    3.4 Sender and recipient indication
  73    3.5 Response control
  74    3.6 Message identification and referral headers
  75    3.7 Other textual headers
  76    3.8 Headers containing dates and times
  77    3.9 Quality information
  78    3.10 Language information
  79    3.11 Size information
  80    3.12 Conversion control
  81    3.13 Encoding information
  82    3.14 Resent-headers
  83    3.15 Security and reliability
  84    3.16 Miscellaneous
  85
  86 4. Acknowledgments
  87
  88 5. References
  89
  90 6. Author's address
  91
  92 Appendix A: Headers sorted by Internet RFC document in which
  93             they appear
  94
  95 Appendix B: Alphabetical index
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114 Palme                                                           [Page 2]
 115 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
 116
 117
 118                          1. Introduction
 119
 120 Many different Internet standards and RFCs define headers which
 121 may occur on Internet Mail Messages and Network News Articles. The
 122 intention of this document is to list all such headers in one
 123 document as an aid to people developing message systems or interested
 124 in Internet Mail standards.
 125
 126 The document contains all headers which the author has
 127 found in the following Internet standards: , RFC 822 [2],
 128 RFC 1036 [3], RFC 1123 [5], RFC 1327 [7], RFC 1496 [8], RFC 1521 [11],
 129 RFC 1766 [12], RFC 1806 [14] and RFC 1864[17]. Note in particular that
 130 heading attributes defined in PEM (RFC 1421-1424) and MOSS (RFC 1848
 131 [16]) are not included. PEM and MOSS headers only appear inside the
 132 body of a message, and thus are not headers in the RFC 822 sense. Mail
 133 attributes in envelopes, i.e. attributes controlling the message
 134 transport mechanism between mail and news servers, are not included.
 135 This means that attributes from SMTP [1], UUCP [18] and NNTP [15] are
 136 not covered either. Headings used only in HTTP [19] are not included
 137 yet, but may be included in future version of this memo. A few
 138 additional headers which often can be found in e-mail headings but are
 139 not part of any Internet standard are also included.
 140
 141 For each header, the document gives a short description and
 142 a reference to the Internet standard or RFC, in which they are defined.
 143
 144 The header names given here are spelled the same way as when they are
 145 actually used. This is usually American but sometimes English spelling.
 146 One header in particular, "Organisation/Organization", occurs in e-mail
 147 headers sometimes with the English and other times with the American
 148 spelling.
 149
 150 The following words are used in this memo with the meaning specified
 151 below:
 152
 153 heading           Formatted text at the top of a message, ended by a
 154                   blank line
 155
 156 header = heading  One field in the heading, beginning with a field
 157 field             name, colon, and followed by the field value(s)
 158
 159 It is my intention to continue updating this document after its
 160 publication as an RFC. The latest version, which may be more up-to-date
 161 (but also less fully checked out) will be kept available for
 162 downloading by anonymous FTP from URL
 163 http://www.dsv.su.se/~jpalme/ietf-mail-attributes.pdf.
 164
 165 Please e-mail me (Jacob Palme <jpalme@dsv.su.se>) if you have noted
 166 headers which should be included in this memo but are not.
 167
 168
 169
 170
 171 Palme                                                           [Page 3]
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 173
 174                  2. Use of gatewaying headers
 175
 176 RFC 1327 defines a number of new headers in Internet mail, which
 177 are defined to map headers which X.400 has but which were
 178 previously not standardized in Internet mail. The fact that a
 179 header occurs in RFC 1327 indicates that it is recommended for
 180 use in gatewaying messages between X.400 and Internet mail, but
 181 does not mean that the header is recommended for messages wholly
 182 within Internet mail. Some of these headers may eventually see
 183 widespread implementation and use in Internet mail, but at the time of
 184 this writing (May 1996) they are not widely implemented or used.
 185
 186 Headers defined in RFC 1036 for use in Usenet News sometimes appear
 187 in mail messages, either because the messages have been gatewayed
 188 from Usenet News to e-mail, or because the messages were written in
 189 combined clients supporting both e-mail and Usenet News in the same
 190 client. These headers are not standardized for use in Internet e-mail
 191 and should be handled with caution by e-mail agents.
 192
 193
 194
 195
 196                       3. Table of headers
 197
 198 3.1 Phrases used in the tables
 199
 200
 201 "not for general        Used to mark headers which are defined in RFC
 202 usage"                  1327 for use in messages from or to Internet
 203                         mail/X.400 gateways. These headers have not
 204                         been standardized for general usage in the
 205                         exchange of messages between Internet mail-
 206                         based systems.
 207
 208 "not standardized       Used to mark headers defined only in RFC 1036
 209 for use in e-mail"      for use in Usenet News. These headers have no
 210                         standard meaning when appearing in e-mail,
 211                         some of them may even be used in different
 212                         ways by different software. When appearing in
 213                         e-mail, they should be handled with caution.
 214                         Note that RFC 1036, although generally used as
 215                         a standard for Usenet News, is not an accepted
 216                         IETF standard or on the IETF standards track.
 217
 218 "non-standard"          This header is not specified in any of
 219                         referenced RFCs which define Internet
 220                         protocols, including Internet Standards, draft
 221                         standards or proposed standards. The header
 222                         appears here because it often appears in e-
 223                         mail or Usenet News. Usage of these headers is
 224                         not in general recommended.
 225
 226
 227
 228 Palme                                                           [Page 4]
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 230
 231 "discouraged"           This header, which is non-standard, is known
 232                         to create problems and should not be
 233                         generated. Handling of such headers in
 234                         incoming mail should be done with great
 235                         caution.
 236
 237 "controversial"         The meaning and usage of this header is
 238                         controversial, i.e. different implementors
 239                         have chosen to implement the header in
 240                         different ways. Because of this, such headers
 241                         should be handled with caution and
 242                         understanding of the different possible
 243                         interpretations.
 244
 245 "experimental"          This header is used for newly defined headers,
 246                         which are to be tried out before entering the
 247                         IETF standards track. These should only be
 248                         used if both communicating parties agree on
 249                         using them. In practice, some experimental
 250                         protocols become de-facto-standards before
 251                         they are made into IETF standards.
 252
 253
 254
 255 3.2 Trace information
 256 Used to convey the information       Return-Path:    RFC 821,
 257 from the MAIL FROM envelope                          RFC 1123: 5.2.13.
 258 attribute in final delivery, when
 259 the message leaves the SMTP
 260 environment in which "MAIL FROM"
 261 is used.
 262
 263 Trace of MTAs which a message has    Received:       RFC 822: 4.3.2,
 264 passed.                                              RFC 1123: 5.2.8.
 265
 266 List of MTAs passed.                 Path:           RFC 1036: 2.2.6,
 267                                                      only in Usenet
 268                                                      News, not in e-
 269                                                      mail.
 270
 271 Trace of distribution lists          DL-Expansion-   RFC 1327, not for
 272 passed.                              History-        general usage.
 273                                      Indication:
 274
 275 3.3 Format and control
 276 information
 277
 278 An indicator that this message is    MIME-Version:   RFC 1521: 3.
 279 formatted according to the MIME
 280 standard, and an indication of
 281 which version of MIME is
 282 utilized.
 283
 284
 285
 286 Palme                                                           [Page 5]
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 288
 289 Special Usenet News actions.         Control:        RFC 1036: 2.1.6,
 290                                                      only in Usenet
 291                                                      News, not in e-
 292                                                      mail.
 293
 294 Which body part types occur in       Original-       RFC 1327, not for
 295 this message.                        Encoded-        general usage.
 296                                      Information-
 297                                      Types:
 298
 299 Controls whether this message may    Alternate-      RFC 1327, not for
 300 be forwarded to alternate            Recipient:      general usage.
 301 recipients such as a postmaster
 302 if delivery is not possible to
 303 the intended recipient. Default:
 304 Allowed.
 305
 306 Whether recipients are to be told    Disclose-       RFC 1327, not for
 307 the names of other recipients of     Recipients:     general usage.
 308 the same message. This is
 309 primarily an X.400 facility. In
 310 X.400, this is an envelope
 311 attribute and refers to
 312 disclosure of the envelope
 313 recipient list. Disclosure of
 314 other recipients is in Internet
 315 mail done via the To:, cc: and
 316 bcc: headers.
 317
 318 Whether a MIME body part is to be    Content-        RFC 1806,
 319 shown inline or is an attachment;    Disposition:    experimental
 320 can also indicate a suggested
 321 filename for use when saving an
 322 attachment to a file.
 323
 324 3.4 Sender and recipient
 325 indication
 326
 327 Authors or persons taking            From:           RFC 822: 4.4.1,
 328 responsibility for the message.                      RFC 1123: 5.2.15-
 329                                                      16, 5.3.7,
 330                                                      RFC 1036 2.1.1
 331
 332 Name of the moderator of the         Approved:       RFC 1036: 2.2.11,
 333 newsgroup to which this message                      not standardized
 334 is sent; necessary on an article                     for use in e-mail.
 335 sent to a moderated newsgroup to
 336 allow its distribution to the
 337 newsgroup members. Also used on
 338 certain control messages, which
 339 are only performed if they are
 340 marked as Approved.
 341
 342
 343
 344 Palme                                                           [Page 6]
 345 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
 346
 347 The person or agent submitting       Sender:         RFC 822: 4.4.2,
 348 the message to the network, if                       RFC 1123: 5.2.15-
 349 other than shown by the From:                        16, 5.3.7.
 350 header.
 351
 352 Primary recipients.                  To:             RFC 822: 4.5.1,
 353                                                      RFC 1123: 5.2.15-
 354                                                      16, 5.3.7.
 355
 356 Secondary, informational             cc:             RFC 822: 4.5.2,
 357 recipients. (cc = Carbon Copy)                       RFC 1123. 5.2.15-
 358                                                      16, 5.3.7.
 359
 360 Recipients not to be disclosed to    bcc:            RFC 822: 4.5.3,
 361 other recipients. (bcc = Blind                       RFC 1123: 5.2.15-
 362 Carbon Copy).                                        16, 5.3.7.
 363
 364 In Usenet News: group(s) to which    Newsgroups:     RFC 1036: 2.1.3,
 365 this article was posted.                             not standardized
 366 Some systems provide this header                     and controversial
 367 also in e-mail although it is not                    for use in e-mail.
 368 standardized there.
 369 Unfortunately, the header can
 370 appear in e-mail with two
 371 different and contradictory
 372 meanings:
 373 (a) Indicates the newsgroup
 374 recipient of a message sent to
 375 both e-mail and Usenet News
 376 recipients.
 377 (b) In a personally addressed
 378 reply to a message in a news-
 379 group, indicate the newsgroup in
 380 which this discussion originated.
 381
 382 Inserted by Sendmail when there      Apparently-     Non-standard,
 383 is no "To:" recipient in the         To:             discouraged,
 384 original message, listing                            mentioned in
 385 recipients derived from the                          RFC 1211.
 386 envelope into the message
 387 heading. This behavior is not
 388 quite proper, MTAs should not
 389 modify headings (except inserting
 390 Received lines), and it can in
 391 some cases cause Bcc recipients
 392 to be wrongly divulged to non-Bcc
 393 recipients.
 394
 395 Geographical or organizational       Distribution:   RFC 1036: 2.2.7,
 396 limitation on where this message                     not standardized
 397 can be distributed.                                  for use in e-mail.
 398
 399
 400
 401
 402 Palme                                                           [Page 7]
 403 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
 404
 405 Fax number of the originator.        Fax:,           Non-standard.
 406                                      Telefax:
 407
 408
 409 Phone number of the originator.      Phone:          Non-standard.
 410
 411 Information about the client         Mail-System-    Non-standard.
 412 software of the originator.          Version:,
 413                                      Mailer:,
 414                                      Originating-
 415                                      Client:, X-
 416                                      Mailer, X-
 417                                      Newsreader
 418
 419 3.5 Response control
 420
 421 This header is meant to indicate     Reply-To:       RFC 822: 4.4.3,
 422 where the sender wants replies to                    RFC 1036: 2.2.1
 423 go. Unfortunately, this is                           controversial.
 424 ambiguous, since there are
 425 different kinds of replies, which
 426 the sender may wish to go to
 427 different addresses. In
 428 particular, there are personal
 429 replies intended for only one
 430 person, and group replies,
 431 intended for the whole group of
 432 people who read the replied-to
 433 message (often a mailing list).
 434
 435 Some mail systems use this header
 436 to indicate a better form of the
 437 e-mail address of the sender.
 438 Some mailing list expanders puts
 439 the name of the list in this
 440 header. These practices are
 441 controversial. The personal
 442 opinion of the author of this RFC
 443 is that this header should be
 444 avoided except in special cases,
 445 but this is a personal opinion
 446 not shared by all specialists in
 447 the area.
 448
 449 Used in Usenet News to indicate      Followup-To:    RFC 1036: 2.2.3,
 450 that future discussions (=follow-                    not standardized
 451 up) on an article should go to a                     for use in e-mail.
 452 different set of newsgroups than
 453 the replied-to article. The most
 454 common usage is when an article
 455 is posted to several newsgroups,
 456 and further discussions is to
 457 take place in only one of them.
 458
 459 Palme                                                           [Page 8]
 460 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
 461
 462 In e-mail, this header is used in
 463 a message which is sent to both e-
 464 mail and Usenet News, to show
 465 where follow-up in Usenet news is
 466 wanted. The header does not say
 467 anything about where follow-up in
 468 e-mail is to be sent.
 469
 470 Note that the value of this
 471 header must always be one or more
 472 newsgroup names, never e-mail
 473 addresses.
 474
 475 Address to which notifications       Errors-To:,     Non-standard,
 476 are to be sent and a request to      Return-         discouraged.
 477 get delivery notifications.          Receipt-To:
 478 Internet standards recommend,
 479 however, the use of RCPT TO and
 480 Return-Path, not Errors-To, for
 481 where delivery notifications are
 482 to be sent.
 483
 484 Whether non-delivery report is       Prevent-        RFC 1327, not for
 485 wanted at delivery error. Default    NonDelivery-    general usage.
 486 is to want such a report.            Report:
 487
 488 Whether a delivery report is         Generate-       RFC 1327, not for
 489 wanted at successful delivery.       Delivery-       general usage.
 490 Default is not to generate such a    Report:
 491 report.
 492
 493 Indicates whether the content of     Content-        RFC 1327, not for
 494 a message is to be returned with     Return:         general usage.
 495 non-delivery notifications.
 496
 497 3.6 Message identification and
 498 referral headers
 499
 500 Unique ID of this message.           Message-ID:     RFC 822: 4.6.1
 501                                                      RFC 1036: 2.1.5.
 502
 503 Unique ID of one body part of the    Content-ID:     RFC 1521: 6.1.
 504 content of a message.
 505
 506 Reference to message which this      In-Reply-To:    RFC 822: 4.6.2.
 507 message is a reply to.
 508
 509 Reference to other related           References:     RFC 822: 4.6.3
 510 messages.                                            RFC 1036: 2.1.5.
 511
 512 Reference to previous message        Obsoletes:      RFC 1327, not for
 513 being corrected and replaced.                        general usage.
 514 Compare to "Supersedes:" below.
 515
 516
 517 Palme                                                           [Page 9]
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 519
 520 Commonly used in Usenet News in      Supersedes:     Non-standard.
 521 similar ways to the "Obsoletes"
 522 header described above. In Usenet
 523 News, however, Supersedes causes
 524 a full deletion of the replaced
 525 message in the server, while
 526 Obsoletes is implemented in the
 527 client and often does not remove
 528 the old version of the text.
 529
 530 3.7 Other textual headers
 531
 532 Search keys for data base            Keywords:       RFC 822: 4.7.1
 533 retrieval.                                           RFC 1036: 2.2.9.
 534
 535 Title, heading, subject. Often       Subject:        RFC 822: 4.7.1
 536 used as thread indicator for                         RFC 1036: 2.1.4.
 537 messages replying to or
 538 commenting on other messages.
 539
 540 Comments on a message.               Comments:       RFC 822: 4.7.2.
 541
 542 Description of a particular body     Content-        RFC 1521: 6.2.
 543 part of a message.                   Description:
 544
 545 Organization to which the sender     Organization:   RFC 1036: 2.2.8,
 546 of this message belongs.                             not standardized
 547                                                      for use in e-mail.
 548
 549 See Organization above.              Organisation:   Non-standard.
 550
 551 Short text describing a longer       Summary:        RFC 1036: 2.2.10,
 552 message. Warning: Some mail                          not standardized
 553 systems will not display this                        for use in e-mail,
 554 text to the recipient. Because of                    discouraged.
 555 this, do not use this header for
 556 text which you want to ensure
 557 that the recipient gets.
 558
 559 A text string which identifies       Content-        RFC 1327, not for
 560 the content of a message.            Identifier:     general usage.
 561
 562 3.8 Headers containing dates and
 563 times
 564
 565 The time when a message was          Delivery-       RFC 1327, not for
 566 delivered to its recipient.          Date:           general usage.
 567
 568 In Internet, the date when a         Date:           RFC 822: 5.1,
 569 message was written, in X.400,                       RFC 1123: 5.2.14
 570 the time a message was submitted.                    RFC 1036: 2.1.2.
 571 Some Internet mail systems also
 572 use the date when the message was
 573 submitted.
 574
 575 Palme                                                          [Page 10]
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 577
 578 A suggested expiration date. Can     Expires:        RFC 1036: 2.2.4,
 579 be used both to limit the time of                    not standardized
 580 an article which is not                              for use in e-mail.
 581 meaningful after a certain date,
 582 and to extend the storage of
 583 important articles.
 584
 585 Time at which a message loses its    Expiry-Date:    RFC 1327, not for
 586 validity.                                            general usage.
 587
 588 Latest time at which a reply is      Reply-By:       RFC 1327, not for
 589 requested (not demanded).                            general usage.
 590
 591 3.9 Quality information
 592
 593 Can be "normal", "urgent" or "non-   Priority:       RFC 1327, not for
 594 urgent" and can influence                            general usage.
 595 transmission speed and delivery.
 596
 597 Sometimes used as a priority         Precedence:     Non-standard,
 598 value which can influence                            controversial,
 599 transmission speed and delivery.                     discouraged.
 600 Common values are "bulk" and
 601 "first-class". Other uses is to
 602 control automatic replies and to
 603 control return-of-content
 604 facilities, and to stop mailing
 605 list loops.
 606
 607 A hint from the originator to the    Importance:     RFC 1327, not for
 608 recipients about how important a                     general usage.
 609 message is. Values: High, normal
 610 or low. Not used to control
 611 transmission speed.
 612
 613 How sensitive it is to disclose      Sensitivity:    RFC 1327, not for
 614 this message to other people than                    general usage.
 615 the specified recipients. Values:
 616 Personal, private, company
 617 confidential. The absence of this
 618 header in messages gatewayed from
 619 X.400 indicates that the message
 620 is not sensitive.
 621
 622 Body parts are missing.              Incomplete-     RFC 1327, not for
 623                                      Copy:           general usage.
 624
 625 3.10 Language information
 626
 627 Can include a code for the           Language:       RFC 1327, not for
 628 natural language used in a                           general usage.
 629 message, e.g. "en" for English.
 630
 631
 632
 633 Palme                                                          [Page 11]
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 635
 636 Can include a code for the           Content-        RFC 1766, proposed
 637 natural language used in a           Language:       standard.
 638 message, e.g. "en" for English.
 639
 640 3.11 Size information
 641
 642 Inserted by certain mailers to       Content-        Non-standard,
 643 indicate the size in bytes of the    Length:         discouraged.
 644 message text. This is part of a
 645 format some mailers use when
 646 showing a message to its users,
 647 and this header should not be
 648 used when sending a message
 649 through the net. The use of this
 650 header in transmission of a
 651 message can cause several
 652 robustness and interoperability
 653 problems.
 654
 655 Size of the message.                 Lines:          RFC 1036: 2.2.12,
 656                                                      not standardized
 657                                                      for use in e-mail.
 658
 659 3.12 Conversion control
 660
 661 The body of this message may not     Conversion:     RFC 1327, not for
 662 be converted from one character                      general usage.
 663 set to another. Values:
 664 Prohibited and allowed.
 665
 666 Non-standard variant of              Content-        Non-standard.
 667 Conversion: with the same values.    Conversion:
 668
 669 The body of this message may not     Conversion-     RFC 1327, not for
 670 be converted from one character      With-Loss:      general usage.
 671 set to another if information
 672 will be lost. Values: Prohibited
 673 and allowed.
 674
 675 3.13 Encoding information
 676
 677 Format of content (character set     Content-Type:   RFC 1049,
 678 etc.) Note that the values for                       RFC 1123: 5.2.13,
 679 this header are defined in                           RFC 1521: 4.
 680 different ways in RFC 1049 and in
 681 MIME (RFC 1521), look for the
 682 "MIME-version" header to
 683 understand if Content-Type is to
 684 be interpreted according to RFC
 685 1049 or according to MIME. The
 686 MIME definition should be used in
 687 generating mail.
 688
 689
 690
 691 Palme                                                          [Page 12]
 692 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
 693
 694 Coding method used in a MIME         Content-        RFC 1521: 5.
 695 message body.                        Transfer-
 696                                      Encoding:
 697
 698 Only used with the value             Message-Type:   RFC 1327, not for
 699 "Delivery Report" to indicates                       general usage.
 700 that this is a delivery report
 701 gatewayed from X.400.
 702
 703 Used in several different ways by    Encoding:       RFC 1154,
 704 different mail systems. Some use                     RFC 1505,
 705 it for a kind of content-type                        experimental.
 706 information, some for encoding
 707 and length information, some for
 708 a kind of boundary information,
 709 some in other ways.
 710
 711 3.14 Resent-headers
 712
 713 When manually forwarding a           Resent-Reply-   RFC 822: C.3.3.
 714 message, headers referring to the    To:,
 715 forwarding, not to the original      Resent-From:,
 716 message.  Note: MIME specifies       Resent-
 717 another way of resending             Sender:,
 718 messages, using the "Message"        Resent-From:,
 719 Content-Type.                        Resent-Date:,
 720                                      Resent-To:,
 721                                      Resent-cc:,
 722                                      Resent-bcc:,
 723                                      Resent-
 724                                      Message-ID:
 725
 726 3.15 Security and reliability
 727
 728 Checksum of content to ensure        Content-MD5:    RFC 1864, proposed
 729 that it has not been modified.                       standard.
 730
 731 3.16 Miscellaneous
 732
 733 Name of file in which a copy of      Fcc:            Non-standard.
 734 this message is stored.
 735
 736 Has been automatically forwarded.    Auto-           RFC 1327, not for
 737                                      Forwarded:      general usage.
 738
 739 Can be used in Internet mail to      Discarded-      RFC 1327, not for
 740 indicate X.400 IPM extensions        X400-IPMS-      general usage.
 741 which could not be mapped to         Extensions:
 742 Internet mail format.
 743
 744 Can be used in Internet mail to      Discarded-      RFC 1327, not for
 745 indicate X.400 MTS extensions        X400-MTS-       general usage.
 746 which could not be mapped to         Extensions:
 747 Internet mail format.
 748
 749 Palme                                                          [Page 13]
 750 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
 751
 752
 753                           4. Acknowledgments
 754
 755 Harald Tveit Alvestrand, Ned Freed, Olle Järnefors, Keith Moore, Nick
 756 Smith and several other people have helped me with compiling this list.
 757 I especially thank Ned Freed and Olle Järnefors for their thorough
 758 review and many helpful suggestions for improvements. I alone take
 759 responsibility for any errors which may still be in the list.
 760
 761 An earlier version of this list has been published as part of [13].
 762
 763
 764
 765                             5. References
 766
 767 Ref.    Author, title                                    IETF status
 768                                                          (May 1996)
 769 -----   ---------------------------------------------    -----------
 770 [1]     J. Postel: "Simple Mail Transfer Protocol",      Standard,
 771         STD 10, RFC 821, August 1982.                    Recommended
 772
 773 [2]     D. Crocker: "Standard for the format of ARPA     Standard,
 774         Internet text messages." STD 11, RFC 822,        Recommended
 775         August 1982.
 776
 777 [3]     M.R. Horton, R. Adams: "Standard for             Not an offi-
 778         interchange of USENET messages", RFC 1036,       cial IETF
 779         December 1987.                                   standard,
 780                                                          but in
 781                                                          reality a de-
 782                                                          facto
 783                                                          standard for
 784                                                          Usenet News
 785
 786 [4]     M. Sirbu: "A Content-Type header header for      Standard,
 787         internet messages", RFC 1049, March 1988.        Recommended,
 788                                                          but can in
 789                                                          the future
 790                                                          be expected
 791                                                          to be
 792                                                          replaced by
 793                                                          MIME
 794
 795 [5]     R. Braden (editor): "Requirements for            Standard,
 796         Internet Hosts -- Application and Support",      Required
 797         STD-3, RFC 1123, October 1989.
 798
 799 [6]     D. Robinson, R. Ullman: "Encoding Header         Non-standard
 800         Header for Internet Messages", RFC 1154,
 801         April 1990.
 802
 803
 804
 805
 806
 807 Palme                                                          [Page 14]
 808 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
 809
 810 [7]     S. Hardcastle-Kille: "Mapping between            Proposed
 811         X.400(1988) / ISO 10021 and RFC 822",  RFC       standard,
 812         1327 May 1992.                                   elective
 813
 814 [8]     H. Alvestrand & J. Romaguera: "Rules for         Proposed
 815         Downgrading Messages from X.400/88 to            standard,
 816         X.400/84 When MIME Content-Types are Present     elective
 817         in the Messages", RFC 1496, August 1993.
 818
 819 [9]     A. Costanzo: "Encoding Header Header for         Non-standard
 820         Internet Messages", RFC 1154, April 1990.
 821
 822 [10]    A. Costanzo, D. Robinson: "Encoding Header       Experimental
 823         Header for Internet Messages", RFC 1505,
 824         August 1993.
 825
 826 [11]    N. Borenstein & N. Freed: "MIME (Multipurpose    Draft
 827         Internet Mail Extensions) Part One:              Standard,
 828         Mechanisms for Specifying and Describing the     elective
 829         Format of Internet Message Bodies", RFC 1521,
 830         Sept 1993.
 831
 832 [12]    H. Alvestrand: "Tags for the Identification      Proposed
 833         of Languages", RFC 1766, February 1995.          standard,
 834                                                          elective
 835
 836 [13]    J. Palme: "Electronic Mail", Artech House        Non-standard
 837         publishers, London-Boston January 1995.
 838
 839 [14]    R. Troost, S. Dorner: "Communicating             Experimental
 840         Presentation Information in Internet
 841         Messages: The Content-Disposition Header",
 842         RFC 1806, June 1995.
 843
 844 [15]    B. Kantor, P. Lapsley, "Network News Transfer    Proposed
 845         Protocol: "A Proposed Standard for the Stream-   standard
 846         Based Transmission of News", RFC 977, January
 847         1986.
 848 [16]    1848  PS   S. Crocker, N. Freed, J. Galvin,      Proposed
 849         S. Murphy, "MIME Object Security Services",      standard
 850         RFC 1848, March 1995.
 851
 852 [17]    J. Myers, M. Rose: The Content-MD5 Header        Draft
 853         Header, RFC 1864, October 1995.                  standard
 854
 855 [18]    M. Horton, UUCP mail interchange format          Not an offi-
 856         standard, RFC 976, Januari 1986.                 cial IETF
 857                                                          standard,
 858                                                          but in
 859                                                          reality a de-
 860                                                          facto
 861                                                          standard for
 862                                                          Usenet News
 863
 864
 865 Palme                                                          [Page 15]
 866 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
 867
 868 [19]    T. Berners-Lee, R. Headering, H. Frystyk:        IETF draft
 869         Hypertext Transfer Protocol -- HTTP/1.0,
 870         draft-ietf-http-v10-spec-04.txt.
 871
 872
 873
 874                           6. Author's address
 875
 876 Jacob Palme                          Phone: +46-8-16 16 67
 877 Stockholm University/KTH             Fax: +46-8-783 08 29
 878 Electrum 230                         E-mail: jpalme@dsv.su.se
 879 S-164 40 Kista, Sweden
 880
 881
 882
 883
 884                              Appendix A:
 885 Headers sorted by Internet RFC document in which they appear.
 886
 887
 888 RFC 822
 889 -------
 890
 891 bcc
 892 cc
 893 Comments
 894 Date
 895 From
 896 In-Reply-To
 897 Keywords
 898 Message-ID
 899 Received
 900 References
 901 Reply-To
 902 Resent-
 903 Resent-bcc
 904 Resent-cc
 905 Resent-Date
 906 Resent-From
 907 Resent-From
 908 Resent-Message-ID
 909 Resent-Reply-To
 910 Resent-To
 911 Return-Path
 912 Sender
 913 Sender
 914 Subject
 915 To
 916
 917
 918
 919
 920
 921
 922
 923 Palme                                                          [Page 16]
 924 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
 925
 926 RFC 1036
 927 --------
 928
 929 Approved
 930 Control
 931 Distribution
 932 Expires
 933 Followup-To
 934 Lines
 935 Newsgroups
 936 Organization
 937 Path
 938 Summary
 939
 940 RFC 1049
 941 --------
 942
 943 Content-Type
 944
 945 RFC 1327
 946 --------
 947
 948 Alternate-recipient
 949 Auto-Forwarded
 950 Autoforwarded
 951 Content-Identifier
 952 Content-Return
 953 Conversion
 954 Conversion-With-Loss
 955 Delivery-Date
 956 Discarded-X400-IPMS-Extensions
 957 Discarded-X400-MTS-Extensions
 958 Disclose-Recipients
 959 DL-Expansion-History
 960 Expiry-Date
 961 Generate-Delivery-Report
 962 Importance
 963 Incomplete-Copy
 964 Language
 965 Message-Type Delivery
 966 Obsoletes
 967 Original-Encoded-Information-Types
 968 Prevent-NonDelivery-Report
 969 Priority
 970 Reply-By
 971 Report
 972 Sensitivity
 973
 974 RFC 1505
 975 --------
 976
 977 Encoding
 978
 979
 980 Palme                                                          [Page 17]
 981 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
 982
 983 RFC 1521
 984 --------
 985
 986 Content-Description
 987 Content-ID
 988 Content-Transfer-Encoding
 989 Content-Type
 990 MIME-Version
 991
 992 RFC 1806
 993 --------
 994
 995 Content-Disposition
 996
 997 RFC 1864
 998 --------
 999
1000 Content-MD5
1001
1002 Not Internet standard
1003 ---------------------
1004
1005 Apparently-to
1006 Content-length
1007 Encoding
1008 Errors-To
1009 Return-Receipt-To
1010 Fax
1011 Telefax
1012 Fcc
1013 Mail-System-Version
1014 Mailer
1015 Organisation
1016 Originating-Client
1017 Phone
1018 Supersedes
1019 X-Mailer
1020 X-Newsreader
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039 Palme                                                          [Page 18]
1040 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
1041
1042                              Appendix B:
1043                          Alphabetical index
1044
1045 Section Heading-header
1046 ------- --------------
1047
1048 3.3     Alternate-Recipient
1049 3.4     Apparently-To
1050 3.4     Approved
1051 3.16    Auto-Forwarded
1052 3.4     bcc
1053 3.4     cc
1054         Client, see Originating-Client
1055 3.7     Comments
1056 3.12    Content-Conversion
1057 3.7     Content-Description
1058 3.3     Content-Disposition
1059 3.6     Content-ID
1060 3.7     Content-Identifier
1061 3.10    Content-Language see also Language
1062 3.11    Content-Length
1063 3.15    Content-MD5
1064 3.4     Content-Return
1065 3.13    Content-Transfer-Encoding
1066 3.13    Content-Type
1067 3.3     Control
1068 3.12    Conversion
1069 3.12    Conversion-With-Loss
1070 3.8     Date
1071 3.8     Delivery-Date
1072         Delivery-Report, see Generate-Delivery-Report, Prevent-
1073         Delivery-Report, Non-Delivery-Report, Content-Type
1074         Description, see Content-Description
1075 3.16    Discarded-X400-IPMS-Extensions
1076 3.16    Discarded-X400-MTS-Extensions
1077 3.3     Disclose-Recipients
1078         Disposition, see Content-Disposition
1079 3.4     Distribution
1080 3.2     DL-Expansion-History-Indication
1081 3.13    Encoding see also Content-Transfer-Encoding
1082 3.4     Errors-To
1083 3.8     Expires
1084         Extension see Discarded-X400-IPMS-Extensions, Discarded-
1085         X400-MTS-Extensions
1086 3.4     Fax
1087 3.16    Fcc
1088 3.4     Followup-To
1089         Forwarded, see Auto-Forwarded
1090 3.4     From
1091 3.4     Generate-Delivery-Report
1092         History, see DL-Expansion-History-Indication
1093         ID, see Content-ID and Message-ID
1094         Identifier, see Content-ID and Message-ID
1095
1096
1097 Palme                                                          [Page 19]
1098 \fdraft-ietf-mailext-mail-attributes-04.txt                      May 1996
1099
1100 3.9     Importance
1101 3.6     In-Reply-To
1102 3.9     Incomplete-Copy
1103 3.7     Keywords
1104 3.10    Language see also Content-Language
1105         Length see Content-Length
1106 3.11    Lines
1107 3.4     Mail-System-Version see also X-mailer
1108 3.4     Mailer
1109         MD5 see Content-MD5
1110 3.6     Message-ID
1111 3.13    Message-Type
1112 3.3     MIME-Version
1113 3.4     Newsgroups
1114         Newsreader, see X-Newsreader
1115 3.6     Obsoletes
1116 3.7     Organisation
1117 3.7     Organization
1118 3.3     Original-Encoded-Information-Types
1119 3.4     Originating-Client
1120 3.2     Path
1121 3.4     Phone
1122 3.9     Precedence
1123 3.4     Prevent-NonDelivery-Report
1124 3.9     Priority
1125 3.2     Received
1126         Recipient, see To, cc, bcc, Alternate-Recipient, Disclose-
1127         Recipient
1128 3.6     References
1129 3.8     Reply-By
1130 3.4     Reply-To, see also In-Reply-To, References
1131 3.14    Resent-
1132         Return see also Content-Return
1133 3.2     Return-Path
1134 3.5     Return-Receipt-To
1135 3.4     Sender
1136 3.9     Sensitivity
1137 3.7     Subject
1138 3.7     Summary
1139 3.6     Supersedes
1140 3.4     Telefax
1141 3.4     To
1142         Transfer-Encoding see Content-Transfer-Encoding
1143         Type see Content-Type, Message-Type, Original-Encoded-
1144         Information-Types
1145         Version, see MIME-Version, X-Mailer
1146 3.4     X-Mailer see also Mail-System-Version
1147 3.4     X-Newsreader
1148
1149
1150
1151
1152
1153
1154 Palme                                                          [Page 20]