Plesk 11 auth-smtp with PostFix / mac works, pc doesn't

[rgfincher]

Have upgraded Plesk 9.5.4 to 11.0.4 and found that my PostFix no longer recognises the auth-SMTP usernames/passwords for any accounts, when Microsoft email clients are used. However, it works fine when Apple Mac and iOS clients are used.

Suspect one or more types of password encryption which used to be enabled, are now disabled.
Am fairly new to PostFix (although not to Plesk)

Any ideas?

 

[rgfincher]

Log-line entry:


Nov 11 21:15:48 mail postfix/smtpd[11571]: warning: SASL authentication failure: realm changed: authentication aborted

 

[rgfincher]

More information

This problem seems limited to connections on port 587 (submission port) which our customers mostly use, due to British providers of DSL blocking port 25 to third party servers.

 

[whyers]

ATT and 587

ATT (midwestern US) DSL also blocks port 25, I've found that when port 587 is open, the STARTTLS and not SSL seems to work.