So glad you were able to solve the problem. I ruled out the DL possibility by just using one, internal recipient. But every bit of information helps! ...

No, but I think I'm making progress. Here are some of the things I've tried.

I've used telnet to connect to the SMTP server and have communicated successfully.

I've found the...

Thanks vikingDBA. I've sent the test mail, but haven't checked on the Exchange end. Thanks for the tip!

The comments I've received so far have been helpful in ruling things out. I'm checking the SMTP server via telnet to see if it is relaying properly. If...