I still find myself using MAPI within Outlook in addition to the Exchange connection as well as an IMAPS account. Somehow I’ve been getting along with ISA 2004 and SBS 2003 without that FWC Outlook change. I never new this issue existed. After rereading your information I think I’m confused when you conclude that Secure NAT SMTP/POP connection are denied by default. Both SBS rules for Outgoing POP & SMTP use the All Users group and I didn’t discovered any authentication requirements. Perhaps you could explain a little more about the Secure NAT aspect you discovered.

Thanks