Dequeue POP3 email to Exchange 5 Dialup

Our ISP hosts our mail on a POP3 server. We are trying to retrieve our mail using MS Exchange 5.5 over a dial-up connection. They apparently don’t support ETRN (although they’re not sure about that). Is there a command we can use or does anyone knowhow we can do this. The ISP just doesn’t seem to know what’s going on here.