Deprecation of TLS 1.1 for Email Submission and Access
RFC 8997

Document Type RFC - Proposed Standard (March 2021; No errata)
Updates RFC 8314
Authors Loganaden Velvindron  , Stephen Farrell 
Last updated 2021-03-23
Replaces draft-lvelvindron-tls-for-email
Stream Internet Engineering Task Force (IETF)
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Reviews
Stream WG state Submitted to IESG for Publication
Document shepherd Valery Smyslov
Shepherd write-up Show (last changed 2020-01-15)
IESG IESG state RFC 8997 (Proposed Standard)
Action Holders
(None)
Consensus Boilerplate Yes
Telechat date
Responsible AD Alexey Melnikov
Send notices to Valery Smyslov <valery@smyslov.net>
IANA IANA review state Version Changed - Review Needed
IANA action state No IANA Actions


Internet Engineering Task Force (IETF)                     L. Velvindron
Request for Comments: 8997                                 cyberstorm.mu
Updates: 8314                                                 S. Farrell
Category: Standards Track                         Trinity College Dublin
ISSN: 2070-1721                                               March 2021

         Deprecation of TLS 1.1 for Email Submission and Access

Abstract

   This specification updates the current recommendation for the use of
   the Transport Layer Security (TLS) protocol to provide
   confidentiality of email between a Mail User Agent (MUA) and a Mail
   Submission Server or Mail Access Server.  This document updates RFC
   8314.

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/rfc8997.

Copyright Notice

   Copyright (c) 2021 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
   2.  Conventions Used in This Document
   3.  Updates to RFC 8314
   4.  IANA Considerations
   5.  Security Considerations
   6.  References
     6.1.  Normative References
     6.2.  Informative References
   Acknowledgements
   Authors' Addresses

1.  Introduction

   [RFC8314] defines the minimum recommended version of TLS as version
   1.1.  Due to the deprecation of TLS 1.1 in [RFC8996], this
   recommendation is no longer valid.  Therefore, this document updates
   [RFC8314] so that the minimum version for TLS is TLS 1.2.

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.  Updates to RFC 8314

   OLD:

   |  4.1.  Deprecation of Services Using Cleartext and TLS Versions
   |  Less Than 1.1

   NEW:

   |  4.1.  Deprecation of Services Using Cleartext and TLS Versions
   |  Less Than 1.2

   OLD:

   |  As soon as practicable, MSPs currently supporting Secure Sockets
   |  Layer (SSL) 2.x, SSL 3.0, or TLS 1.0 SHOULD transition their users
   |  to TLS 1.1 or later and discontinue support for those earlier
   |  versions of SSL and TLS.

   NEW:

   |  As soon as practicable, MSPs currently supporting Secure Sockets
   |  Layer (SSL) 2.x, SSL 3.0, TLS 1.0, or TLS 1.1 SHOULD transition
   |  their users to TLS 1.2 or later and discontinue support for those
   |  earlier versions of SSL and TLS.

   In Section 4.1 of [RFC8314], the text should be revised from:

   OLD:

   |  One way is for the server to refuse a ClientHello message from any
   |  client sending a ClientHello.version field corresponding to any
   |  version of SSL or TLS 1.0.

   NEW:

   |  One way is for the server to refuse a ClientHello message from any
   |  client sending a ClientHello.version field corresponding to any
   |  version of SSL or TLS earlier than TLS 1.2.

   OLD:

   |  It is RECOMMENDED that new users be required to use TLS version
   |  1.1 or greater from the start.  However, an MSP may find it
   |  necessary to make exceptions to accommodate some legacy systems
   |  that support only earlier versions of TLS or only cleartext.

   NEW:

   |  It is RECOMMENDED that new users be required to use TLS version
   |  1.2 or greater from the start.  However, an MSP may find it
   |  necessary to make exceptions to accommodate some legacy systems
   |  that support only earlier versions of TLS or only cleartext.

   OLD:

   |  If, however, an MUA provides such an indication, it MUST NOT
   |  indicate confidentiality for any connection that does not at least
   |  use TLS 1.1 with certificate verification and also meet the
   |  minimum confidentiality requirements associated with that account.

   NEW:

   |  If, however, an MUA provides such an indication, it MUST NOT
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