The sendmail/linuxconf thing is getting scarier. I had SMTP Auth and virtual hosting working. They broke. I dorked around, they worked, they broke, and now looking deeper into sendmail.cf, I don’t think they ever should have been working together. However they definitely were.
Unfortunately, now that I know that what I did shouldn’t work, it never will again. Which means I really have to learn sendmail. Not on my list of cool things to do.
Have you considered qmail? http://cr.yp.to/