Windows

Go into exchange administrator.

Go to the Site Name, Then Connections, double click on Internet Mail Service to get the properties.

Click on the Routing Tab, choose Add, type in the domain name and set to the first option, Inbound.

You willneed to manually add that address to whomever needs it for your already existing mailboxes, but it will service inbound mail for that other domain as well.

To accept e-mail inbound from two (or more FQDNs) domains:

1. Open the Exchange Admin application
2. Open up the Connections
3. Open the Internet Mail Service (Ex5.5)/Internet Mail Connector (Ex5.0 nd earlier)
4. Open the Routing tab of the IMS/IMS
5. Add the second (third, fourth, etc.) domain to the list of inbound domains

Additionally, you need to ensure that your DNS MX records for the second domain point at your Exchange server. Lastly, you will want to add Internet addresses for new/existing mailboxes that relate to the second domain. This is done on the E-Mail Addresses tab of the respective Recipients.

Good luck