We are running Exchange 2000 on MS Server 2003. Recently, one of our employees told me that he can't receive emails from one of our clients from whom he was able to receive emails before. I've controlled exchange message tracking and found out the following records for this sender:
SMTP: Message submitted to advanced queuing.
SMTP: Started Message Submission.
SMTP: Message submitted to categorizer.
SMTP: Message categorized and and queued for routing.
SMTP: Non-Delivered Report (NDR) Generated.
I've done a test on DNSSTUFF and it revealed several FAILs and WARNINGs for the sender's domain. However, that sender is still able to send emails to other recipients not in our domain. However, DNSSTUFF for our domain passes all tests without failures except some warnings.
What could be the reason and how can I set up my exchange to still receive emails from this particular sender?