draft-ietf-emailcore-as-10.txt   draft-ietf-emailcore-as-11.txt 
EMAILCORE J.C. Klensin, Ed. EMAILCORE J.C. Klensin, Ed.
Internet-Draft Internet-Draft
Intended status: Standards Track K. Murchison, Ed. Intended status: Standards Track K. Murchison, Ed.
Expires: 3 January 2025 Fastmail Expires: 4 January 2025 Fastmail
E. Sam, Ed. E. Sam, Ed.
2 July 2024 3 July 2024
Applicability Statement for IETF Core Email Protocols Applicability Statement for IETF Core Email Protocols
draft-ietf-emailcore-as-10 draft-ietf-emailcore-as-11
Abstract Abstract
Electronic mail is one of the oldest Internet applications that is Electronic mail is one of the oldest Internet applications that is
still in very active use. While the basic protocols and formats for still in very active use. While the basic protocols and formats for
mail transport and message formats have evolved slowly over the mail transport and message formats have evolved slowly over the
years, events and thinking in more recent years have supplemented years, events and thinking in more recent years have supplemented
those core protocols with additional features and suggestions for those core protocols with additional features and suggestions for
their use. This Applicability Statement describes the relationship their use. This Applicability Statement describes the relationship
among many of those protocols and provides guidance and makes among many of those protocols and provides guidance and makes
recommendations for the use of features of the core protocols. recommendations for the use of features of the core protocols.
Open Issues Open Issues
* #40 - Recommended SMTP Extensions (https://github.com/ietf-wg- * #40 - Recommended SMTP Extensions (https://github.com/ietf-wg-
emailcore/emailcore/issues/40): Requires discussion of current/new emailcore/emailcore/issues/40): Requires discussion of current/new
text. text. Do we remove DSN from the list?
* #78 - Advice against using URL %-encoding on non-ASCII email * #78 - Advice against using URL %-encoding on non-ASCII email
addresses (https://github.com/ietf-wg-emailcore/emailcore/ addresses (https://github.com/ietf-wg-emailcore/emailcore/
issues/78): Is the "final" proposed text in Section 4.2 issues/78): Is the "final" proposed text in Section 4.2
sufficient? sufficient?
* #79 - Add Internationalization Considerations Section * #79 - Add Internationalization Considerations Section
(https://github.com/ietf-wg-emailcore/emailcore/issues/79): (https://github.com/ietf-wg-emailcore/emailcore/issues/79):
Requires discussion of any new text. Requires discussion of any new text.
skipping to change at page 2, line 17 skipping to change at page 2, line 17
Requires discussion of any new text. Requires discussion of any new text.
* #92 - CNAME handling in "5.1. Locating the Target Host" * #92 - CNAME handling in "5.1. Locating the Target Host"
(https://github.com/ietf-wg-emailcore/emailcore/issues/92): (https://github.com/ietf-wg-emailcore/emailcore/issues/92):
Requires discussion of any new text. Requires discussion of any new text.
* #93 - "7.3. VRFY, EXPN, and Security" should point to SMTP AUTH * #93 - "7.3. VRFY, EXPN, and Security" should point to SMTP AUTH
RFC (https://github.com/ietf-wg-emailcore/emailcore/issues/93): RFC (https://github.com/ietf-wg-emailcore/emailcore/issues/93):
Requires discussion of any new text. Requires discussion of any new text.
* #94 - Use of Quoted Strings (https://github.com/ietf-wg-
emailcore/emailcore/issues/94): Requires discussion of proposed
text.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on 3 January 2025. This Internet-Draft will expire on 4 January 2025.
Copyright Notice Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
skipping to change at page 3, line 7 skipping to change at page 3, line 13
provided without warranty as described in the Revised BSD License. provided without warranty as described in the Revised BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Conventions Used in This Document . . . . . . . . . . . . 4 1.1. Conventions Used in This Document . . . . . . . . . . . . 4
2. Applicability of Some SMTP Provisions . . . . . . . . . . . . 4 2. Applicability of Some SMTP Provisions . . . . . . . . . . . . 4
2.1. Handling of the Domain Argument to the EHLO Command . . . 5 2.1. Handling of the Domain Argument to the EHLO Command . . . 5
2.2. Use of Address Literals . . . . . . . . . . . . . . . . . 5 2.2. Use of Address Literals . . . . . . . . . . . . . . . . . 5
2.3. Use of Addresses in Top-Level Domains . . . . . . . . . . 5 2.3. Use of Addresses in Top-Level Domains . . . . . . . . . . 5
2.4. Use of SMTP Extensions . . . . . . . . . . . . . . . . . 5 2.4. Use of SMTP Extensions . . . . . . . . . . . . . . . . . 6
3. Applicability of Message Format Provisions . . . . . . . . . 6 3. Applicability of Message Format Provisions . . . . . . . . . 6
3.1. Use of Empty Quoted Strings . . . . . . . . . . . . . . . 6 3.1. Use of Empty Quoted Strings . . . . . . . . . . . . . . . 6
3.2. Use of Received Header Fields . . . . . . . . . . . . . . 6 3.2. Use of Received Header Fields . . . . . . . . . . . . . . 7
3.2.1. Generation . . . . . . . . . . . . . . . . . . . . . 7 3.2.1. Generation . . . . . . . . . . . . . . . . . . . . . 7
3.2.2. Consumption . . . . . . . . . . . . . . . . . . . . . 7 3.2.2. Consumption . . . . . . . . . . . . . . . . . . . . . 7
3.3. Handling of Trace Header Fields . . . . . . . . . . . . . 7 3.3. Handling of Trace Header Fields . . . . . . . . . . . . . 7
4. Use of Email Addresses . . . . . . . . . . . . . . . . . . . 7 4. Use of Email Addresses . . . . . . . . . . . . . . . . . . . 8
4.1. Case-Sensitivity, Delimiters, and Mailbox Equivalency . . 7 4.1. Case-Sensitivity, Delimiters, and Mailbox Equivalency . . 8
4.2. Use of non-ASCII Characters . . . . . . . . . . . . . . . 8 4.2. Use of non-ASCII Characters . . . . . . . . . . . . . . . 9
4.3. Use and Validation in HTML and Other Contexts . . . . . . 9 4.3. Use and Validation in HTML and Other Contexts . . . . . . 9
5. Use of Multipurpose Internet Mail Extensions (MIME) . . . . . 9 5. Use of Multipurpose Internet Mail Extensions (MIME) . . . . . 10
6. Confidentiality and Authentication with SMTP . . . . . . . . 10 6. Confidentiality and Authentication with SMTP . . . . . . . . 10
6.1. Optional Confidentiality . . . . . . . . . . . . . . . . 10 6.1. Optional Confidentiality . . . . . . . . . . . . . . . . 11
6.2. Required Confidentiality, with Receiving Server 6.2. Required Confidentiality, with Receiving Server
Authentication . . . . . . . . . . . . . . . . . . . . . 11 Authentication . . . . . . . . . . . . . . . . . . . . . 11
6.3. Message-Level Authentication . . . . . . . . . . . . . . 11 6.3. Message-Level Authentication . . . . . . . . . . . . . . 12
6.4. SMTP Authentication . . . . . . . . . . . . . . . . . . . 12 6.4. SMTP Authentication . . . . . . . . . . . . . . . . . . . 12
6.5. Message-Level Confidentiality . . . . . . . . . . . . . . 12 6.5. Message-Level Confidentiality . . . . . . . . . . . . . . 12
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9. Security Considerations . . . . . . . . . . . . . . . . . . . 13 9. Security Considerations . . . . . . . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
10.1. Normative References . . . . . . . . . . . . . . . . . . 13 10.1. Normative References . . . . . . . . . . . . . . . . . . 13
10.2. Informative References . . . . . . . . . . . . . . . . . 13 10.2. Informative References . . . . . . . . . . . . . . . . . 13
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 16 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 16
A.1. Changes from draft-klensin-email-core-as-00 (2020-03-30) to A.1. Changes from draft-klensin-email-core-as-00 (2020-03-30) to
draft-ietf-emailcore-as-00 . . . . . . . . . . . . . . . 16 draft-ietf-emailcore-as-00 . . . . . . . . . . . . . . . 16
A.2. Changes from draft-ietf-emailcore-as-00 (2020-10-06) to A.2. Changes from draft-ietf-emailcore-as-00 (2020-10-06) to
-01 . . . . . . . . . . . . . . . . . . . . . . . . . . 16 -01 . . . . . . . . . . . . . . . . . . . . . . . . . . 16
A.3. Changes from draft-ietf-emailcore-as-01 (2021-04-09) to A.3. Changes from draft-ietf-emailcore-as-01 (2021-04-09) to
-02 . . . . . . . . . . . . . . . . . . . . . . . . . . 16 -02 . . . . . . . . . . . . . . . . . . . . . . . . . . 17
A.4. Changes from draft-ietf-emailcore-as-02 (2021-08-06) to A.4. Changes from draft-ietf-emailcore-as-02 (2021-08-06) to
-03 . . . . . . . . . . . . . . . . . . . . . . . . . . 16 -03 . . . . . . . . . . . . . . . . . . . . . . . . . . 17
A.5. Changes from draft-ietf-emailcore-as-03 (2022-01-31) to A.5. Changes from draft-ietf-emailcore-as-03 (2022-01-31) to
-04 . . . . . . . . . . . . . . . . . . . . . . . . . . 17 -04 . . . . . . . . . . . . . . . . . . . . . . . . . . 17
A.6. Changes from draft-ietf-emailcore-as-04 (2022-05-21) to A.6. Changes from draft-ietf-emailcore-as-04 (2022-05-21) to
-05 . . . . . . . . . . . . . . . . . . . . . . . . . . 17 -05 . . . . . . . . . . . . . . . . . . . . . . . . . . 17
A.7. Changes from draft-ietf-emailcore-as-05 (2022-10-24) to A.7. Changes from draft-ietf-emailcore-as-05 (2022-10-24) to
-06 . . . . . . . . . . . . . . . . . . . . . . . . . . 17 -06 . . . . . . . . . . . . . . . . . . . . . . . . . . 17
A.8. Changes from draft-ietf-emailcore-as-06 (2022-11-07) to A.8. Changes from draft-ietf-emailcore-as-06 (2022-11-07) to
-07 . . . . . . . . . . . . . . . . . . . . . . . . . . 17 -07 . . . . . . . . . . . . . . . . . . . . . . . . . . 18
A.9. Changes from draft-ietf-emailcore-as-07 (2023-03-13) to A.9. Changes from draft-ietf-emailcore-as-07 (2023-03-13) to
-08 . . . . . . . . . . . . . . . . . . . . . . . . . . 18 -08 . . . . . . . . . . . . . . . . . . . . . . . . . . 18
A.10. Changes from draft-ietf-emailcore-as-08 (2023-12-18) to A.10. Changes from draft-ietf-emailcore-as-08 (2023-12-18) to
-09 . . . . . . . . . . . . . . . . . . . . . . . . . . 18 -09 . . . . . . . . . . . . . . . . . . . . . . . . . . 18
A.11. Changes from draft-ietf-emailcore-as-09 (2024-07-02) to A.11. Changes from draft-ietf-emailcore-as-09 (2024-07-02) to
-10 . . . . . . . . . . . . . . . . . . . . . . . . . . 18 -10 . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 A.12. Changes from draft-ietf-emailcore-as-10 (2024-07-03) to
-11 . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
This document is an Applicability Statement [RFC2026], Section 3.2 This document is an Applicability Statement [RFC2026], Section 3.2
that provides guidance in the use of the Internet's core email that provides guidance in the use of the Internet's core email
specifications, the Simple Mail Transfer Protocol (SMTP) specifications, the Simple Mail Transfer Protocol (SMTP)
[I-D.ietf-emailcore-rfc5321bis] and the Internet Message Format (IMF) [I-D.ietf-emailcore-rfc5321bis] and the Internet Message Format (IMF)
[I-D.ietf-emailcore-rfc5322bis], and some extensions that have been [I-D.ietf-emailcore-rfc5322bis], and some extensions that have been
built on them. In order to promote interoperability amongst senders, built on them. In order to promote interoperability amongst senders,
receivers, and intermediaries, it includes discussions and receivers, and intermediaries, it includes discussions and
skipping to change at page 18, line 40 skipping to change at page 18, line 51
emailcore/emailcore/issues/38) emailcore/emailcore/issues/38)
* Applied "final" proposed text for issue #78 - Advice against using * Applied "final" proposed text for issue #78 - Advice against using
URL %-encoding on non-ASCII email addresses (https://github.com/ URL %-encoding on non-ASCII email addresses (https://github.com/
ietf-wg-emailcore/emailcore/issues/78) ietf-wg-emailcore/emailcore/issues/78)
* Applied proposed text for issue #84 - Handling of Trace Header * Applied proposed text for issue #84 - Handling of Trace Header
Fields by MUAs (https://github.com/ietf-wg-emailcore/emailcore/ Fields by MUAs (https://github.com/ietf-wg-emailcore/emailcore/
issues/84) issues/84)
A.12. Changes from draft-ietf-emailcore-as-10 (2024-07-03) to -11
* Added Open Issue #94 - Use of Quoted Strings (https://github.com/
ietf-wg-emailcore/emailcore/issues/94)
Authors' Addresses Authors' Addresses
John C Klensin (editor) John C Klensin (editor)
1770 Massachusetts Ave, Ste 322 1770 Massachusetts Ave, Ste 322
Cambridge, MA 02140 Cambridge, MA 02140
United States of America United States of America
Phone: +1 617 245 1457 Phone: +1 617 245 1457
Email: john-ietf@jck.com Email: john-ietf@jck.com
Kenneth Murchison (editor) Kenneth Murchison (editor)
Fastmail US LLC Fastmail US LLC
1429 Walnut Street - Suite 1201 1429 Walnut Street - Suite 1201
Philadelphia, PA 19102 Philadelphia, PA 19102
United States of America United States of America
Email: murch@fastmailteam.com Email: murch@fastmailteam.com
E Sam (editor) E Sam (editor)
Email: winshell64@gmail.com Email: winshell64@gmail.com
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