7.20. Filtering Messages Based on Recipient
Problem
You need to filter incoming messages based on the recipient.
Solution
Using a graphical user interface
Open the Exchange System Manager (Exchange System Manager.msc).
Expand Global Settings, right-click Message Delivery, and select Properties. Click the Recipient Filtering tab.
Click Add and add an address to filter for. You can use wildcards to block entire domains. Click OK.
If you want to automatically reject messages for addresses in your domain namespaces that do not have corresponding recipient objects in Active Directory, click the Filter recipients who are not in the Directory checkbox.
Click OK.
Discussion
There are two main uses for recipient filtering: preventing external senders from sending mail to particular mail-enabled recipients and preventing mail for nonexistent recipients from ever entering your Exchange organization. Recipient filtering is an organization-wide setting; any restrictions you create will be propagated to all servers and apply for every anonymously submitted inbound message submission to the organization. Exchange returns the "550 5.7.1 Requested action not taken; mailbox not available" error when a message is submitted to a filtered recipient.
See Also
MS KB 823866 (How to configure connection filtering to use Realtime Block Lists (RBLs) and how to configure recipient filtering in Exchange 2003)