The built-in Mail application does not seem to support TLS using STARTTLS for IMAP on standard IMAP port 143. This is the only option my email server offers, and it works for every other email client I have ever used.

In the UI there is an option called SSL that insist on using the legacy port 993.

Can someone confirm this?

Any hope for us STARTTLS users?

  • According to a MS rep, this issue has been resolved and a patch is available: "This issue has been fixed in the latest update of communication package version 16.4.4406.1205. Please update communication app through store-> update. You can find the version information through Settings->About on the right edge when Mail/Calendar/People/Messaging App is on foreground." See: answers.microsoft.com/en-us/windows/forum/windows_8-ecoms/… – james.garriss Jan 22 '13 at 16:42

I found out that STARTTLS support will come in Mail for Windows 10. Mail will still prefer SSL connections—even though they’re deprecated now—over TLS when available.

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According to this forum post on Microsoft Community, many people are complaining that STARTTLS isn't working for them either. A Microsoft representative claims on page 3 that the Mail app will exhibit the following behavior in relation to STARTTLS:

If Server support STARTTLS, Mail app will do unsecured connection follow with TLS handshake.

If Server doesn’t support STARTTLS, Mail app will send email with unsecured connection.

Later he states:

FYI, mail app always connect server with secured connection whenever it is possible (STARTTLS capability was represented in this case).

We are looking to patch this issue with fallbacking to unsecured connection if TLS connection failed.

Based on that, it seems like it's possible to use STARTTLS, but many others are claiming they cannot get it to work either.

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  • Your are describing the Mail app’s handling of STARTTLS for SMTP (outgoing) connections. I was asking about STARTTLS for IMAP (incoming) connections. – Aeyoun Nov 2 '12 at 19:54
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    I raised the same question on the Microsoft Answers forums, though. So thank you for bringing that up. – Aeyoun Nov 2 '12 at 20:02
  • The questions in that forum address both SMTP and IMAP/POP. – james.garriss Jan 22 '13 at 16:40

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