There has been a rise of backscatter spam (incorrect automated bounce messages sent by mail servers, typically as a side effect of incoming spam.). Recipients of such messages see them as a form of unsolicited bulk e-mail since they were not solicited by the recipients, are very similar to each other and are delivered in bulk quantities. Systems that generate e-mail backscatter can end up being listed on various DNSBLs and block lists. This creates a lot of headaches for Exchange admins. One way to battle it, is to disable Non-Delivery reports, generated by the server.
You can also forward a copy of your NDR to specific users:
Restart the MS Exchange Routing Engine and SMTP services:
In today's world, most emails are spam and there are several reasons why its a good idea to drop bounce emails silently:
However, quoting RFC 5321, section 6.2:
As discussed in Section 7.8 and Section 7.9 below, dropping mail without notification of the sender is permitted in practice. However, it is extremely dangerous and violates a long tradition and community expectations that mail is either delivered or returned. If silent message-dropping is misused, it could easily undermine confidence in the reliability of the Internet's mail systems. So silent dropping of messages should be considered only in those cases where there is very high confidence that the messages are seriously fraudulent or otherwise inappropriate.
So use it wisely.