[Dovecot] Problems with Apple Mail: Enter Password for Account "..."

[Frank Röhm]

Hello

I have on Ubuntu 12.04 a postfix 2.9.3-2 mailserver with dovecot 2.0.19

I get email from my pc (thunderbird), my smartphone (k9mail) and my
MacBook (Apple Mail 4.6 - 1085 on Mac OS 10.6.8) all with IMAP and SSL.

All is working normally but sometimes I get an error message from my
MacBook, which is irritating. It says this (more or less):

"Enter Password for Account
"..."

The IMAP-Server "..." rejected the password
for user "..."

Enter your password again or cancel.
...
o Remember this password in my keychain"

The password was NOT wrong, but anyway, if reenter it, Apple Mail won't
accept it, the message will come again and again.

I guess that dovecot blocks apple mail maybe because the other two
clients try to login at the same time?

Is there any setting where I could adjust this blocking (if it is
blocking) in dovecot?
Only if this really is the reason.

The issue is coming not regularily but when it comes, often for half an
hour I cannot check mails for this account (other accounts on apple mail
won't be touched).
If I restart Apple Mail, the problem could be fixed, but maybe not.

In the logfiles of Dovecot I don't find anything about this.

Thank you and kind regards

frank