SMTP TLS Reporting
RFC 8460

Document Type RFC - Proposed Standard (September 2018; No errata)
Last updated 2018-09-26
Replaces draft-brotman-smtp-tlsrpt
Stream IETF
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Reviews
Stream WG state Submitted to IESG for Publication
Document shepherd Valery Smyslov
Shepherd write-up Show (last changed 2018-03-05)
IESG IESG state RFC 8460 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Alexey Melnikov
Send notices to Leif Johansson <leifj@sunet.se>, Valery Smyslov <valery@smyslov.net>
IANA IANA review state IANA - Not OK
IANA action state RFC-Ed-Ack
Internet Engineering Task Force (IETF)                       D. Margolis
Request for Comments: 8460                                  Google, Inc.
Category: Standards Track                                     A. Brotman
ISSN: 2070-1721                                            Comcast, Inc.
                                                         B. Ramakrishnan
                                                              Oath, Inc.
                                                                J. Jones
                                                         Microsoft, Inc.
                                                               M. Risher
                                                            Google, Inc.
                                                          September 2018

                           SMTP TLS Reporting

Abstract

   A number of protocols exist for establishing encrypted channels
   between SMTP Mail Transfer Agents (MTAs), including STARTTLS, DNS-
   Based Authentication of Named Entities (DANE) TLSA, and MTA Strict
   Transport Security (MTA-STS).  These protocols can fail due to
   misconfiguration or active attack, leading to undelivered messages or
   delivery over unencrypted or unauthenticated channels.  This document
   describes a reporting mechanism and format by which sending systems
   can share statistics and specific information about potential
   failures with recipient domains.  Recipient domains can then use this
   information to both detect potential attacks and diagnose
   unintentional misconfigurations.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8460.

Margolis, et al.             Standards Track                    [Page 1]
RFC 8460                   SMTP TLS Reporting             September 2018

Copyright Notice

   Copyright (c) 2018 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.

Margolis, et al.             Standards Track                    [Page 2]
RFC 8460                   SMTP TLS Reporting             September 2018

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Related Technologies  . . . . . . . . . . . . . . . . . . . .   5
   3.  Reporting Policy  . . . . . . . . . . . . . . . . . . . . . .   6
     3.1.  Example Reporting Policy  . . . . . . . . . . . . . . . .   8
       3.1.1.  Report Using MAILTO . . . . . . . . . . . . . . . . .   8
       3.1.2.  Report Using HTTPS  . . . . . . . . . . . . . . . . .   8
   4.  Reporting Schema  . . . . . . . . . . . . . . . . . . . . . .   8
     4.1.  Report Time Frame . . . . . . . . . . . . . . . . . . . .   9
     4.2.  Delivery Summary  . . . . . . . . . . . . . . . . . . . .  10
       4.2.1.  Success Count . . . . . . . . . . . . . . . . . . . .  10
       4.2.2.  Failure Count . . . . . . . . . . . . . . . . . . . .  10
     4.3.  Result Types  . . . . . . . . . . . . . . . . . . . . . .  10
       4.3.1.  Negotiation Failures  . . . . . . . . . . . . . . . .  10
       4.3.2.  Policy Failures . . . . . . . . . . . . . . . . . . .  11
       4.3.3.  General Failures  . . . . . . . . . . . . . . . . . .  11
       4.3.4.  Transient Failures  . . . . . . . . . . . . . . . . .  12
     4.4.  JSON Report Schema  . . . . . . . . . . . . . . . . . . .  12
     4.5.  Policy Samples  . . . . . . . . . . . . . . . . . . . . .  15
   5.  Report Delivery . . . . . . . . . . . . . . . . . . . . . . .  15
     5.1.  Report Filename . . . . . . . . . . . . . . . . . . . . .  16
     5.2.  Compression . . . . . . . . . . . . . . . . . . . . . . .  17
     5.3.  Email Transport . . . . . . . . . . . . . . . . . . . . .  17
       5.3.1.  Example Report  . . . . . . . . . . . . . . . . . . .  19
     5.4.  HTTPS Transport . . . . . . . . . . . . . . . . . . . . .  19
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