Configure the Internet Mail Service for multiple domains

More businesses register multiple domain names than ever before because it's cheap and easy to do. Some users have several e-mail addresses, all with different domain names but delivered via the same mail server. If you aren't hosting more than one domain on your Exchange server, you probably will in the near future.

Follow these steps to configure the Internet Mail Service (IMS) to support multiple domains in Exchange 5.5:

1. From the Exchange Server Administrator program, navigate to the Connections container, and double-click the Internet Mail Service object.
2. From the Internet Mail Service Properties dialog box, select the Routing tab, and click Add.
3. Enter the domain you want to add in the E-mail Sent To This Domain field, select the Should Be Accepted As "Inbound" option, and click OK.
4. Repeat Steps 2 and 3 for each domain you need to support. When you're finished adding domains, click OK to close the Internet Mail Service Properties dialog box.
5. Stop and restart the Microsoft Exchange Internet Mail Service to make your changes take effect.

In order for mail from the new domains to be delivered to your Exchange server, you'll need to do some DNS work. The DNS server that's authoritative for each domain you host must point the domain's MX record to the same host A record that contains the IP address of your SMTP host. If you don't host your own DNS, contact your ISP about making these changes.