We have a Windows 2003 SBS server that the Exchange 2003 has been dormant for some time since a previous system administrator had chosen to outsource the mail hosting. The current users have been Popping the mail from this host to their Outlook clients.
The client wanted to begin to host mail internally now. I've requested and received the MX record change to point to our outside address.
Comcast Business Class Internet service. Cable Modem is configured to place our Cicso/Linksys EA6500 router in the DMZ. The EA6500 is configured to pass ports 110, 25, 443, 80, 143, 593, 135 and 445 via the "Single Port Forwarding" setup in the "Apps and Gaming" Security tab.
I am able to telnet from an outside server to the POP3 and SMTP ports.
My issue is that some of the users can authenticate using POP3 but some are not able. The error is "-ERR Logon failure: unknown user name or bad password."
All the users can authenticate to the Outlook Web Access portal.
I have run the CEICW a few times and still no luck. I've changed the passwords for the users that could not connect and that has not made any difference.
Exchange 2003 is updated to SP2.