I am helping a remote office with some networking and server work, and without explanation their email program (Outlook 2003) stopped allowing clients to receive emails (POP3). After contacting web host tech support to check the email server, and all seemed fine there, I did further testing from my location. I am in a different town, and from a command line I can telnet to their email server to port 110 and receive connection. From their location, using command line, I can telnet to the email server on port 25, port 143, but not on port 110 - connection is refused without much explanation.
So, my first thought is - a firewall problem. They use a Watchguard Firebox x10e, and there have been no changes made to the settings in it. There is no filter on outbound traffic, and I have open SMTP port 25 for inbound. The POP3 setting for inbound has always been port 25, is this correct? I have tried changing to 110, and it still does not solve the current problem, so I changed it back to 25, the way it has always been. So, either way this does not appear to be the cause of our current problem.
Does anyone know what else I can check? The ISP is Qwest, and there have been some known line problems the last few days, in certain areas, but they are having no other internet problems at this remote office. Only the POP3 port 110 connection fails. Email server tech support is at a loss, and so am I, so I would appreciate any other clues.