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.
What it is
Deprecates TLS 1.0 and 1.1 for mail submission and access, leaving 1.2 as the floor.
What it solves
Old TLS versions stayed enabled long after they stopped being defensible, because turning them off breaks old clients.
What it means to operate
Check what your submission service still accepts. This is the document to cite when somebody asks why an old device stopped connecting.
Domain check reports what a domain publishes for TLS, and whether the policy behind it resolves. Open domain check
Normative requirements
Every sentence in this RFC carrying an RFC 2119 keyword, with the section it came from.
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.