Can’t send/receive e-mail from Dial-Up

I am running Window2000 on a laptop using Outlook 98 to connect to Exchange 5.5 server. On the network I can connect to Exchange fine, but I am unable to send/receive e-mail from dialing into the network via RAS. This was working fine, but suddenlystopped several weeks ago. I have checked the Outlook profile and everything appears to be setup correctly. What am I missing?