Private email address redirects are used for any legitimate senders who's mail servers can't handle grey listing.  There are usually very few senders who's messages bounce, and using pre-configured private email address redirects is simpler than white listing.  In fact, using the private email addresses in all cases that would not potentially result in the addresses being harvested into spammer emailing lists can be a policy that is regularly followed by the company to begin with.

This means the company would use j.doe@xyz.company.com on business cards and in trusted online databases, while j.doe@company.com would be used in online databases and public locations that were not trusted to be free of spammer email address harvesting.

The following grey list reports on your server are available to an administrator from your company.

All blocks for a mail user
All blocks for a mail sender
All blocks for a mail server's IP address
All blocks