What major e-mail clients actually make use of DNS SRV autoconfiguration?

Question

You can use RFC 6186 to implement autodiscovery for mail. It is however unclear to me at this point what major clients are actually using this protocol?

So RFC 6186 describes autodiscovery using these DNS records. For example:

SRV _submission._tcp.{mydomain.com}  0  1 587 {mailserver}
SRV _imap._tcp.{mydomain.com}        0  0   0 .
SRV _imaps._tcp.{mydomain.com}       0  1 993 {mailserver}
SRV _pop3._tcp.{mydomain.com}        0  0   0 .
SRV _pop3s._tcp.{mydomain.com}       10 1 995 {mailserver}

Major clients of which I already suspect they do not use it.

• Outlook uses it's own autdiscovery method (using _autodiscover._tcp.{mydomain.com}).
• Thunderbird uses it's own method. None of those involve the RFC. See this page.
• iOS mail does not seem to use any autodiscovery method: but I am not 100% sure about this! Although one can point a iOS user to a mobileconfig configuration file.
• Android' stock mail app does not seem to support autodiscovery.

Would love to know what major tools do use it! Thanks.

Labret

Have you found any information on this in the meantime? This unanswered SO question was the only thing that I could find, unfortunately. It's a pity that support for this standard is so bad as it should be an absolute no-brainer. It's a typical bootstrapping problem, though. I couldn't find many domains that actually provide such a record (with dig srv _submission._tcp.gmail.com +short, for example). Support for Mozilla's autoconfig subdomain seems even worse. – Navvy

I concluded that it made no sense for us to implement this RFC. What we ended up implementing was: a) autoconfig for Thunderbird b) autodiscover for Outlook and c) a profile you can download for Apple products. And that does the trick pretty well. – Labret

According to this thread, new Outlook version (from 2016?) use these SRV records. Not tested yet. – Anaemic

@Anaemic That is kinda similar to what I written about. Although some numbers are slightly different. So I am not convinced that that will solve it for non-Exchange cases. Having said that: I did not try it out with those exact values! So if somebody that reads this is true desperate, you can try that (and report back please ;))! – Labret

There's also _smtp._tls. for MTA-STS and TLS reporting. support.google.com/a/answer/9276512?hl=en – Terri

Notes on why Thunderbird doesn't use it: bugzilla.mozilla.org/show_bug.cgi?id=342242 they say they won't do it without DNSSEC and that's a very valid reason. Maybe Apple has the same concerns about it. – Terri

Thunderbird link is dead. – Contradance