IMAP Trouble: "Test Account Settings..." works but

I’m trying to get IMAP working on Outlook2k7/Vista. The account appears to be working properly: I click the “Test Account Settings…” button and get a successful login and test email sent. Yet when I try to send normally I get an error: "Task ‘ - Sending’ reported error (0x80040201): ‘Unknown Error 0x80040201’ "

Has anyone else seen this? Any idea what is going on here?



Found my answer here:

The problem is unique to those of us coming from an Exchange Server environment.