Quoting Robert JR <roundcube222@alaadin.org>:

After 10 mins of unactivity of pop3 , dovecot disconnect the user
(-ERR Disconnected for inactivity.)

What is the option in the config file which control the unactivity
logout time ? becuase i want to decrease the inactivity time

To 5 mins instead of 10 mins

You can't (at least without hacking the code). The POP3 specification
**requires** a minimum of 10 minutes before an autologout occurs (RFC
1939 [3]):

http://tools.ietf.org/html/rfc1939#section-3

michael