I stepped in to help a friend with his small business network and they are running SBS 2000 with ISA 2000 configured as their firewall, etc .... They are no longer running Exchange server internally, and they moved to use externally hosted POP3 mail from another provider. The tech who switched them from Exchange to external POP3 did not remove Exchange completely from the system (which you may not be able to with SBS 2000 anyways), but he did set them up with this external POP3 mail.
They have been using this external POP3 mail for about 6 months with no issues at all. Yesterday he called me and asked if I could help them get their POP3 mail back. For some reason most of them are no longer able to download their POP3 mail from the externally hosted mail provider via port 110. I can download POP3 mail from the server and there is ONE client that can do it as well! It seems to me that something changed internally that is blocking them from hitting Port 110 externally for POP3 mail. Everyone is not using the firewall client, but it doesn't seem to matter. The one person who can access it does have the client installed, but another person with the client and identical client and workstation settings can't get POP3. Any idea what is going on? How can I open up POP3 completely? If I switch their IP to bypass ISA completely and go direct to the ISP router, it works fine.
I am not familiar with ISA server, but I checked the system and I see these things:
- There is a Protocol Rule called POP3 that is set for Array, Action - Allow, Protocol - POP3, Applies to Any Request - Always. - There is a Protocol Definition called POP3, Port 110 TCP, Outbound, that is set up
What am I missing here? What can I do to fix this issue?