Thanks to my friends at Lotus, I've discovered a fun diversion to while away the afternoon. Anyone can play! Here's how:

1. Go to this page
   
2. Sign up for a trial Domino Web Access account
   
3. Try to send a message to an external SMTP user
   
4. Get an error message
   
5. Lather. Rinse. Repeat.
   

Update: This works properly now, and Domino Web Access is actually pretty impressive as a web client. I'd really like to see a neutral evaluation of DWA against OWA from the standpoint of an average user's ability to discover and use its features.