I got the error when I tried to login with email client, Outlook Express, but I couldn't retrieve any emails from server...
Aug 1 20:32:26 eglory pop3-login: Disconnected [::ffff:192.168.0.20]
Aug 1 20:33:28 eglory pop3-login: Disconnected: Inactivity [::ffff:192.168.0.20]
Aug 1 21:16:53 eglory ctl_mboxlist: DBERROR: reading /var/lib/imap/db/skipstamp, assuming the worst: No such file or directory
Aug 1 21:16:53 eglory ctl_mboxlist: skiplist: recovered /var/lib/imap/mailboxes.db (0 records, 144 bytes) in 0 seconds