I helped deploying Exchange 2010 for single server installations few months back. The admin called me this morning and he reported that the organization was getting up to 200 emails in the postmaster mailbox every day but only 5% of them are to valid recipients.
I hade previously installed Anti-Spam Agent so this is easy to tackle with Recipient Validation
Be enabling Recipient Validation I can also reduce the load on the server and the amount of Non-Delivery Reports sent out by the server. IT also allows Exchange 2010 to reject unknown recipients immediately rather than letting the server accept the message, attempt to deliver it, fail and then deliver to the postmaster mailbox.
Since this is a single server install with no Edge server this has to be done on the server the holds all the roles including the Hub Transport server.
If you have Anti-span installed you enable recipient validation with this simple command
- Set-RecipientFilterConfig -RecipientValidationEnabled $true
If you haven’t installed Anti-Spam agent already, this is how it´s done:
- Open the Exchange Management Shell and navigate to:
- C:\Program Files\Microsoft\Exchange Server\V14\Scripts
- Run this PS script:
- Restart the Exchange Transport service with this command (or via services)
- Restart-Service MSExchangeTransport
You can also use EMC to enable Recipient validation via GUI
- EMC > Organization Configuration > Hub Transport > Anti-span
double click Recipient Filtering
- Click Blocked Recipients tap and select the box next to "Block messages sent to recipients that do not exist in the directory
- Click ok and your all done….
You can try to send to firstname.lastname@example.org before and after to see the difference