I have set up a Exch2003-front-end-server sitting in the DMZ. It provides Outlook Web Access for employees outside in the internet. The mailboxes are sitting on a different server, inside our firewall protected intranet. With Outlook Web Access this works fine.
But when I try to get access to the mailboxes through POP3, I cannot log into the front-end-server. This doesn't even work from the Outlook Express installed on that Exch2003-front-end-server itself.
When I connect with "telnet 127.0.0.1 110", the server is responding with its name and "+OK". Then I can send my user -name, but after sending the password I get a "-ERR Connect attempt failed. Server may be down or too busy to respond."