LAN clients have problems accessing the POP3/IMAP4 server
A missing DNS reverse lookup zone for your LAN can be the reason for problems when LAN clients try to access mailboxes on
DEFENDO. Check the POP3/IMAP4 log in "Monitoring -> Log files" for messages like "Connection timed out while reading line".
Further information on DNS reverse lookup related problems can be found in article "Configuration checklist".