Update:
First of all, our server has Threads version 7.0.2 intsalled, I was mistaken in my first post.
After clearing the SMTP cache, I was able to use the UBB.Classic software to generate emails and successfully deliver to qmail servers. I still can't get the Threads forum to deliver for qmail servers only.
If anyone else is experiencing this problem with Threads 7.0.2 on Win 2003 IIS6, please let me know. It's possible that others are having this problem and don't even realize it. One would have to look through SMTP logs to even know that there is a problem, unless they are contacted by a registrant who didn't recieve their registration email.
