Network Working Group A. Melnikov Internet-Draft Isode Ltd Intended status: Standards Track 13 May 2025 Expires: 14 November 2025 Updates to SMTP related IANA registries draft-melnikov-smtp-iana-cleanup-01 Abstract While EMAILCORE working group was working on update to SMTP specification, it became clear that existing entries in SMTP related registries are missing information or contain stale information and need to be updated. This document updates such entries. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 14 November 2025. Copyright Notice Copyright (c) 2025 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Melnikov Expires 14 November 2025 [Page 1] Internet-Draft Abbreviated Title May 2025 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . 2 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 2 3.1. Updates to the "Simple Mail Transfer Protocol (SMTP) Service Extensions" registry . . . . . . . . . . . . . . 3 3.1.1. Updates to the "References" field . . . . . . . . . . 3 3.1.2. Updates to the "EHLO Parameters" field . . . . . . . 3 3.1.3. Updates to the "Message submission Use and Values" field . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1.4. Updates to the "Additional verbs", "MAIL/RCPT Parameter Values" fields . . . . . . . . . . . . . . . . . . . 3 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. Normative References . . . . . . . . . . . . . . . . . . 8 5.2. Informative References . . . . . . . . . . . . . . . . . 9 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction While EMAILCORE working group was working on update to SMTP specification [I-D.ietf-emailcore-rfc5321bis], it became clear that existing entries in SMTP related registries are missing information or contain stale information and need to be updated. This document updates such entries, assuming IANA actions specified in [I-D.ietf-emailcore-rfc5321bis] were already performed. This document doesn't do any restructuring to existing SMTP related entries. 2. Conventions Used in This Document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 3. IANA Considerations Melnikov Expires 14 November 2025 [Page 2] Internet-Draft Abbreviated Title May 2025 3.1. Updates to the "Simple Mail Transfer Protocol (SMTP) Service Extensions" registry Updates to the "Simple Mail Transfer Protocol (SMTP) Service Extensions" registry are described as an ordered list of steps that should be performed sequentually. Each step is described by a subsection of this section. 3.1.1. Updates to the "References" field IANA is requested to change values of the "References" field for "EXPN" and "HELP" extensions to [I-D.ietf-emailcore-rfc5321bis]. The "References" field values for "SEND", "SOML", "SAML" and "TURN" remain unchanged, as they were obsoleted and there are no newer reference than RFC 821. 3.1.2. Updates to the "EHLO Parameters" field IANA is requested to update the following values in this field: 1. The value corresponding to the DELIVERBY extension should be changed to "A comma separated list of options (optional)", as per [RFC2852]. 2. The value corresponding to the FUTURERELEASE extension should be changed to "max-future-release-interval and max-future-release- date-time", as per [RFC4865]. 3. The value corresponding to the LIMITS extension should be changed to "List of limits", as per [RFC9422]. 3.1.3. Updates to the "Message submission Use and Values" field IANA is requested to update values of the "Message submission Use and Values" field corresponding to "HELP", "BURL", "FUTURERELEASE", "SMTPUTF8", "MT-PRIORITY", "RRVS", "REQUIRETLS" and "LIMITS" extensions to "MAY". 3.1.4. Updates to the "Additional verbs", "MAIL/RCPT Parameter Values" fields IANA is requested to update "Additional verbs" and "MAIL/RCPT Parameter Values" fields as per the table specified below. Information for relevant fields was extracted from existing RFCs describing corresponding SMTP Extensions. Melnikov Expires 14 November 2025 [Page 3] Internet-Draft Abbreviated Title May 2025 +=====================+============+================================+ | EHLO Keyword | Additional | MAIL/RCPT Parameter Values | | | verbs | | +=====================+============+================================+ | SEND | SEND | none | +---------------------+------------+--------------------------------+ | SOML | SOML | none | +---------------------+------------+--------------------------------+ | SAML | SAML | none | +---------------------+------------+--------------------------------+ | EXPN | EXPN | none | +---------------------+------------+--------------------------------+ | HELP | HELP | none | +---------------------+------------+--------------------------------+ | TURN | TURN | none | +---------------------+------------+--------------------------------+ | 8BITMIME | none | BODY parameter to MAIL | | | | command | +---------------------+------------+--------------------------------+ | SIZE | none | SIZE parameter to MAIL | | | | command | +---------------------+------------+--------------------------------+ | CHUNKING | BDAT | none | +---------------------+------------+--------------------------------+ | BINARYMIME | none | BODY parameter to MAIL | | | | command (an extra choice | | | | was added) | +---------------------+------------+--------------------------------+ | CHECKPOINT | none | TRANSID parameter to the | | | | MAIL command | +---------------------+------------+--------------------------------+ | DELIVERBY | none | BY parameter to MAIL | | | | command | +---------------------+------------+--------------------------------+ | PIPELINING | none | none | +---------------------+------------+--------------------------------+ | DSN | none | NOTIFY and ORCPT | | | | parameters to RCPT | | | | command. RET and ENVID | | | | parameters to MAIL command | +---------------------+------------+--------------------------------+ | ETRN | ETRN | none | +---------------------+------------+--------------------------------+ | ENHANCEDSTATUSCODES | none | none | +---------------------+------------+--------------------------------+ | STARTTLS | STARTTLS | none | +---------------------+------------+--------------------------------+ | NO-SOLICITING | none | SOLICIT parameter to MAIL | Melnikov Expires 14 November 2025 [Page 4] Internet-Draft Abbreviated Title May 2025 | | | command | +---------------------+------------+--------------------------------+ | MTRK | none | MTRK parameters to MAIL | | | | command. Also see DSN | | | | extension parameters | +---------------------+------------+--------------------------------+ | SUBMITTER | none | SUBMITTER parameters to | | | | MAIL command | +---------------------+------------+--------------------------------+ | ATRN | ATRN | none | +---------------------+------------+--------------------------------+ | AUTH | AUTH | AUTH parameter to MAIL | | | | command | +---------------------+------------+--------------------------------+ | BURL | BURL | none | +---------------------+------------+--------------------------------+ | FUTURERELEASE | none | HOLDFOR and HOLDUNTIL | | | | parameters to MAIL | | | | command. | +---------------------+------------+--------------------------------+ | UTF8SMTP | none | One optional parameter, | | | | ALT-ADDRESS, is added to | | | | the MAIL and RCPT commands | +---------------------+------------+--------------------------------+ | CONPERM | none | CONPERM parameter to MAIL | | | | command | +---------------------+------------+--------------------------------+ | CONNEG | none | CONNEG parameter to RCPT | | | | command | +---------------------+------------+--------------------------------+ | SMTPUTF8 | none | SMTPUTF8 parameter to the | | | | MAIL command | +---------------------+------------+--------------------------------+ | MT-PRIORITY | none | MT-PRIORITY parameter to | | | | MAIL command | +---------------------+------------+--------------------------------+ | RRVS | none | RRVS parameter to RCPT | | | | command | +---------------------+------------+--------------------------------+ | REQUIRETLS | none | REQUIRETLS parameter to | | | | MAIL command | +---------------------+------------+--------------------------------+ | LIMITS | none | none | +---------------------+------------+--------------------------------+ Table 1 Melnikov Expires 14 November 2025 [Page 5] Internet-Draft Abbreviated Title May 2025 IANA is further requested to update "Length Added" fields as per the table specified below. Information for this field was either extracted or calculated from information in existing RFCs describing corresponding SMTP Extensions. Melnikov Expires 14 November 2025 [Page 6] Internet-Draft Abbreviated Title May 2025 +===============+========+========================================+ | EHLO Keyword | Length | Comment | | | Added | | +===============+========+========================================+ | SIZE | 26 | https://datatracker.ietf.org/doc/html/ | | | | rfc1870#section-3 | +---------------+--------+----------------------------------------+ | CHUNKING | 0 | https://datatracker.ietf.org/doc/html/ | | | | rfc3030#section-2 | +---------------+--------+----------------------------------------+ | BINARYMIME | 16 | https://datatracker.ietf.org/doc/html/ | | | | rfc3030#section-3 | +---------------+--------+----------------------------------------+ | CHECKPOINT | 88 | https://datatracker.ietf.org/doc/html/ | | | | rfc1845#section-2 | +---------------+--------+----------------------------------------+ | DELIVERBY | 17 | https://datatracker.ietf.org/doc/html/ | | | | rfc2852#section-2 | +---------------+--------+----------------------------------------+ | MTRK | 40 | https://datatracker.ietf.org/doc/html/ | | | | rfc3885#section-2 | +---------------+--------+----------------------------------------+ | AUTH | 500 | https://datatracker.ietf.org/doc/html/ | | | | rfc4954#section-3 | +---------------+--------+----------------------------------------+ | FUTURERELEASE | 34 | https://datatracker.ietf.org/doc/html/ | | | | rfc4865#section-3 | +---------------+--------+----------------------------------------+ | UTF8SMTP | 460 | https://datatracker.ietf.org/doc/html/ | | | | rfc5336#section-3.1 | +---------------+--------+----------------------------------------+ | SMTPUTF8 | 10 | https://datatracker.ietf.org/doc/html/ | | | | rfc6531#section-3.1 | +---------------+--------+----------------------------------------+ | MT-PRIORITY | 15 | https://datatracker.ietf.org/doc/html/ | | | | rfc6710#section-3 | +---------------+--------+----------------------------------------+ | RRVS | 33 | https://datatracker.ietf.org/doc/html/ | | | | rfc7293#section-3.1 | +---------------+--------+----------------------------------------+ | REQUIRETLS | 11 | https://www.rfc-editor.org/rfc/ | | | | rfc8689.html#name-iana-considerations | +---------------+--------+----------------------------------------+ Table 2 TBD: Calculate "Length Added" when not specified in existing RFCs. Also possibly merge this with the previous table? Melnikov Expires 14 November 2025 [Page 7] Internet-Draft Abbreviated Title May 2025 4. Security Considerations This document only specifies IANA related actions, thus it doesn't directly affect security on SMTP or its extensions. However better documentation of SMTP extensions in IANA registries can, hopefully, lead to better and more secure implementations. 5. References 5.1. Normative References [I-D.ietf-emailcore-rfc5321bis] Klensin, J. C., "Simple Mail Transfer Protocol", Work in Progress, Internet-Draft, draft-ietf-emailcore-rfc5321bis- 43, 28 April 2025, . [RFC1845] Crocker, D., Freed, N., and A. Cargille, "SMTP Service Extension for Checkpoint/Restart", RFC 1845, DOI 10.17487/RFC1845, September 1995, . [RFC1870] Klensin, J., Freed, N., and K. Moore, "SMTP Service Extension for Message Size Declaration", STD 10, RFC 1870, DOI 10.17487/RFC1870, November 1995, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC2852] Newman, D., "Deliver By SMTP Service Extension", RFC 2852, DOI 10.17487/RFC2852, June 2000, . [RFC3030] Vaudreuil, G., "SMTP Service Extensions for Transmission of Large and Binary MIME Messages", RFC 3030, DOI 10.17487/RFC3030, December 2000, . [RFC3885] Allman, E. and T. Hansen, "SMTP Service Extension for Message Tracking", RFC 3885, DOI 10.17487/RFC3885, September 2004, . Melnikov Expires 14 November 2025 [Page 8] Internet-Draft Abbreviated Title May 2025 [RFC4865] White, G. and G. Vaudreuil, "SMTP Submission Service Extension for Future Message Release", RFC 4865, DOI 10.17487/RFC4865, May 2007, . [RFC5336] Yao, J., Ed. and W. Mao, Ed., "SMTP Extension for Internationalized Email Addresses", RFC 5336, DOI 10.17487/RFC5336, September 2008, . [RFC6409] Gellens, R. and J. Klensin, "Message Submission for Mail", STD 72, RFC 6409, DOI 10.17487/RFC6409, November 2011, . [RFC6531] Yao, J. and W. Mao, "SMTP Extension for Internationalized Email", RFC 6531, DOI 10.17487/RFC6531, February 2012, . [RFC6710] Melnikov, A. and K. Carlberg, "Simple Mail Transfer Protocol Extension for Message Transfer Priorities", RFC 6710, DOI 10.17487/RFC6710, August 2012, . [RFC7293] Mills, W. and M. Kucherawy, "The Require-Recipient-Valid- Since Header Field and SMTP Service Extension", RFC 7293, DOI 10.17487/RFC7293, July 2014, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8689] Fenton, J., "SMTP Require TLS Option", RFC 8689, DOI 10.17487/RFC8689, November 2019, . [RFC9422] Freed, N. and J. Klensin, "The LIMITS SMTP Service Extension", RFC 9422, DOI 10.17487/RFC9422, February 2024, . 5.2. Informative References [RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, DOI 10.17487/RFC5321, October 2008, . Melnikov Expires 14 November 2025 [Page 9] Internet-Draft Abbreviated Title May 2025 Appendix A. Acknowledgements Thank you to John Klensin and Tero Kivinen for suggestions, comments and corrections on this document. Tero Kivinen provided initial version of the table with Length Added values for various SMTP extensions. Author's Address Alexey Melnikov Isode Ltd 14 Castle Mews Hampton TW12 2NP United Kingdom Email: alexey.melnikov@isode.com Melnikov Expires 14 November 2025 [Page 10]