Simple Mail Transfer Protocol
draft-klensin-rfc5321bis-00
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Active Internet-Draft (individual)
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John Klensin
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2019-12-02
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draft-ietf-emailcore-rfc5321bis
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(None)
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(None)
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pdf
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htmlized
bibtex
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(No stream defined) |
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Consensus Boilerplate |
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Unknown
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RFC Editor Note |
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(None)
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IESG |
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I-D Exists
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Network Working Group J. Klensin
Internet-Draft December 2, 2019
Obsoletes: 5321, 1846, 7504 (if
approved)
Updates: 1123 (if approved)
Intended status: Standards Track
Expires: June 4, 2020
Simple Mail Transfer Protocol
draft-klensin-rfc5321bis-00
Abstract
This document is a specification of the basic protocol for Internet
electronic mail transport. It consolidates, updates, and clarifies
several previous documents, making all or parts of most of them
obsolete. It covers the SMTP extension mechanisms and best practices
for the contemporary Internet, but does not provide details about
particular extensions. Although SMTP was designed as a mail
transport and delivery protocol, this specification also contains
information that is important to its use as a "mail submission"
protocol for "split-UA" (User Agent) mail reading systems and mobile
environments.
Note on Reading This Working Draft
This working draft contains a relatively complete trace of
significant changes since RFC 2821. CREF comments marked "[2821]" or
"[2821bis]" are pre-RFC 5321 and can be safely ignored unless there
is some reason to reopen the related issues. Those notes on 2821
will be removed (and this note modified) in the -01 draft, which will
be posted with a 3 December date. It otherwise not expected to
differ from this one -- readers should take their pick. Anything
marked "[5321bis]" is current. In general, unless those are marked
with "[[Note in Draft", in the contents of an "Editor's note", or are
in the "Errata Summary" appendix, they are just notes on changes that
have already been made and where the changes originated. Comments
identified as "2821ter" arose after the Last Call on what became
RFC5321, sometimes before AUTH48 on that document or a bit later.
Those, of course, should still be reviewed. Surviving comments about
rfc5321bis-00 followed by a letter indicate intermediate working
versions of this draft and can be ignored unless the origin of
changes is important. As one can tell from the dates (when they are
given), this document has been periodically updated over a very long
period of time.
Klensin Expires June 4, 2020 [Page 1]
Internet-Draft SMTP December 2019
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 June 4, 2020.
Copyright Notice
Copyright (c) 2019 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 Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Transport of Electronic Mail . . . . . . . . . . . . . . 5
1.2. History and Context for This Document . . . . . . . . . . 5
1.3. Document Conventions . . . . . . . . . . . . . . . . . . 7
2. The SMTP Model . . . . . . . . . . . . . . . . . . . . . . . 7
2.1. Basic Structure . . . . . . . . . . . . . . . . . . . . . 7
2.2. The Extension Model . . . . . . . . . . . . . . . . . . . 10
2.2.1. Background . . . . . . . . . . . . . . . . . . . . . 10
2.2.2. Definition and Registration of Extensions . . . . . . 11
2.2.3. Special Issues with Extensions . . . . . . . . . . . 12
2.3. SMTP Terminology . . . . . . . . . . . . . . . . . . . . 12
2.3.1. Mail Objects . . . . . . . . . . . . . . . . . . . . 12
2.3.2. Senders and Receivers . . . . . . . . . . . . . . . . 13
2.3.3. Mail Agents and Message Stores . . . . . . . . . . . 13
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