When emailing different companies, we receive intermittent bouncebacks. These are few, about 1-2 a week that I am aware of, and many times from the same company (different people), but not always.
The error is:
The following recipient(s) could not be reached:
firstname.lastname@example.org on 8/6/2007 10:30 AM
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<domain.com #5.5.0 smtp;530 authentication required for relay (#5.7.1)>
We are running SBS 2003 with Exchange. I'm not knowledgeable in Exchange or email, and not sure where to start to diagonse this problem. Thank you!