I have a VB.Net program that sends an email to someone with status info. For some reason, I get an error every so often. This error is very speratic and I can't seem to track it down. The message is..

The server rejected one or more recipient
addresses. The server response was: 550 client.

Has anyone else run into this problem before? It does not happen all the time. I can try to resend the email (in the applicaiton) and it usually works fine the second time I try with no changes. Any ideas?

Thanks