[Dovecot] Dovecot doesnot disconnect at end of pop3 session

Hello,

I have 3 users checking same email account using pop3 (outlook express)

suddenly after some hours , users are unable to disconnect from pop3 after checking mail

So i telnet to the pop3 and found that the issue is true but i do not know the reason

telnet mymail.com 110 user username pass password list quit

all commands work except the quit command, Dovecot hang at this point !!!

Why Dovecot hang on receiving the Quit command !!! and doesnot disconnect !!

Any help is greatly appreciated.

Thanks.