Yes, it seems to have been my account settings - I had to change the smtp setting to my new ISP's instead of my old one (whose email address I am still using). Thanks very much - phew!
I recently got broadband access using an ADSL modem. Everything works fine, except that Entourage will now no longer send emails. When I disconnect the ADSL modem and connect via the computer's internal modem, everything works fine again. But when I reconnect the ADSL modem I have the same...