Hi VideoGuy, I saw that post, but it didn't really help. I did, however, just figure it out. Here goes:
When you test on your local machine, you do need to authenticate, and you need to set the host name to mail.yourdomain.com. On my machine, I test with the ASP.NET 2.0 development Web server, and I have SMTP services running.
Then when you publish to your site, you DO NOT authenticate, and you also change the host name to localhost.
Gee, if only someone at LP made this information available. I hope this post saves others the hours of trial and error (and frustration) that I endured.