Postfix immediately closing connection for one client

connectionimappostfixsmtp

I have a problem with one client on my mail server (Postfix, Dovecot, Spamassassin, Postgrey).

They can log in to pick IMAP e-mail up, but they can't send through the outgoing SMTP server. The imap-login line looks just like any other client login (domain and IPs changed for privacy):

dovecot: imap-login: Login: user=<mel@domain>, method=PLAIN, rip=<remote IP>, lip=<local IP>, mpid=18965, TLS, session=<4r5aO35BbcjCI9ti>

But the following line is:

dovecot: imap(mel@domain): Connection closed (IDLE running for 0.001 + waiting input for 0.045 secs, 2 B in + 10+10 B out, state=wait-input) in=11 out=366

The client is connecting from an Outlook account, but there are other clients using Outlook without any issues.

As far as I can see the client is successfully logging in (so it's not a username/password problem).

I can't find any information about what the "IDLE running" bit is about, but clearly, the client can't send any e-mail at the moment.

Can someone please explain what this log line is supposed to be telling me and how I can address the issue for my client.

Best Answer

The log line is related to IMAP IDLE and unlikely to tell you anything useful about outgoing messages.
Dovecot (IMAP) doesn't handle outbound information. Postfix (SMTP) does.

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