Microsoft Outlook (on Android) will not connect to postfix (SMTP). In the Android app, you will get the message that an error has occurred. On the postfix side I see that an SSL error occurred:
Jul 17 19:14:54 server postfix/submission/smtpd[5892]: connect from sub.domain.tld[123.123.123.123]
Jul 17 19:14:54 server postfix/submission/smtpd[5892]: SSL_accept error from sub.domain.tld[123.123.123.123]: lost connection
Jul 17 19:14:54 server postfix/submission/smtpd[5892]: lost connection after STARTTLS from sub.domain.tld[123.123.123.123]
Jul 17 19:14:54 server postfix/submission/smtpd[5892]: disconnect from sub.domain.tld[123.123.123.123] ehlo=1 starttls=0/1 commands=1/2
In an attempt to get more information, I increased the loglevel from 1 to 3 and also saw this flying by:
Jul 17 19:49:51 server postfix/submission/smtpd[12560]: sub.domain.tld[123.123.123.123]: TLS cipher list "aNULL:-aNULL:HIGH:MEDIUM:+RC4:@STRENGTH"
Of course I tried both port 587 and 465.
The IMAP (dovecot) connection seems to work (looking at the logs). I assume since SMTP fails, the entire configuration fails. Dovecot log:
Jul 17 19:49:51 server dovecot: imap-login: Login: user=<username@domain.tld>, method=PLAIN, rip=123.123.123.123, lip=123.123.123.122, mpid=12550, TLS, session=<112El8HJeqUtiueK>
Jul 17 19:49:51 server dovecot: imap(username@domain.tld)<12550><112El8HJeqUtiueK>: Logged out in=12 out=445 deleted=0 expunged=0 trashed=0 hdr_count=0 hdr_bytes=0 body_count=0 body_bytes=0
The server works with all other e-mails clients, K-9, Thunderbird and even Microsoft Outlook on the desktop. Just not the official Outlook Android application.
Does anyone have the foggiest idea why this happening and how to fix this?