I have upgraded from 8.0.2 to 8.0.3 (CentOS 6.4) one month ago. By a few days, customers complain that pop3 clients do not receive emails, I can telnet 110 port, the daemon is listening but after username and password connection is hanging; I have to exec

zmmailboxdctl restart
very ugly. IMAP is ok, instead, when POP3 is not working.