I'm managing a Dovecot POP3 server which serves large number of users. Some of these users are in remote locations. I'm getting reports about users whose Thunderbird clients show the number of mails to be downloaded, but disconnects after that.
Server logs shows no corruption about user mailboxes. Only abnormality is only 1 RETR is received, ~10KB of data sent as a reply, nothing downloaded, nothing deleted. Also these users "Disconnect" instead of "Logging out". I cannot find any pointers to my problems. Network connection seems good, server is handling rest of the users with no problems and blazing speed, server hardware is not saturated. I cannot troubleshoot Thunderbird though. I'm just not experienced with it.