RFC 8997 Proposed Standard Transport security

Deprecation of TLS 1.1 for Email Submission and Access

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
Proposed Standard. On the standards track and stable enough to implement against. Most of the email stack stays at this level permanently.
Published
March 2021
Authors
L. Velvindron, S. Farrell
Read it
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Normative requirements

Every sentence in this RFC carrying an RFC 2119 keyword, with the section it came from. 6 must, 4 should, 2 may.

3 Updates to RFC 8314

  • SHOULD| 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.
  • SHOULD| 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.
  • RECOMMENDED| It is RECOMMENDED that new users be required to use TLS version | 1.1 or greater from the start.
  • RECOMMENDED| It is RECOMMENDED that new users be required to use TLS version | 1.2 or greater from the start.
  • MUST NOT| 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.
  • MUST NOT| If, however, an MUA provides such an indication, it MUST NOT | indicate confidentiality for any connection that does not at least | use TLS 1.2 with certificate verification and also meet the | minimum confidentiality requirements associated with that account.
  • MUST| MUAs MUST implement TLS 1.2 [RFC5246] or later.
  • MAYEarlier TLS and | SSL versions MAY also be supported, so long as the MUA requires at | least TLS 1.1 [RFC4346] when accessing accounts that are | configured to impose minimum confidentiality requirements.
  • MUST| MUAs MUST implement TLS 1.2 [RFC5246] or later, e.g., TLS 1.3 | [RFC8446].
  • MAYEarlier TLS and SSL versions MAY also be supported, so | long as the MUA requires at least TLS 1.2 [RFC5246] when accessing | accounts that are configured to impose minimum confidentiality | requirements.
  • MUST| The default minimum expected level of confidentiality for all new | accounts MUST require successful validation of the server's | certificate and SHOULD require negotiation of TLS version 1.1 or | greater.
  • MUST| The default minimum expected level of confidentiality for all new | accounts MUST require successful validation of the server's | certificate and SHOULD require negotiation of TLS version 1.2 or | greater.

Every current email RFC