This article describes how to receive messages from two Simple Mail Transfer Protocol (SMTP) domains in Microsoft Exchange Server 2003 and in Microsoft Exchange 2000 Server. For example, you can use the procedure described in this article if you change your organization name from companya to companyb, and you use companyb.com as your SMTP domain name instead of companya.com. You may need to keep the previous domain name for a few months in case customers send e-mail messages to the previous e-mail addresses.

To receive messages from two Simple Mail Transfer Protocol (SMTP) domains in Exchange Server:

1.	Contact the Internet Service Provider (ISP), and tell them to point both of the domain's MX records to the same Exchange computer. For more information about A and MX records, click the following article number to view the article in the Microsoft Knowledge Base: 153001 (http://support.microsoft.com/kb/153001/) DNS MX records and CNAMEs
2.	Start Exchange System Manager.
3.	Browse to Organization\Recipients\Recipient Policies.
4.	Right-click Default Policy, and then click Properties.
5.	Click the E-Mail Addresses tab, and then click New.
6.	Click SMTP Address, and then click OK.
7.	Verify that the This Exchange Organization is responsible for all mail delivery to this address check box has been selected.
8.	In the Address box, type the new SMTP domain name (for example, @companyb.com), and then click OK.
9.	Click the E-Mail Addresses tab, and then click the new SMTP item to enable it.
10.	Click the SMTP item, and then click Set as Primary. This address is now the sender's reply SMTP address.
11.	Click OK to apply the change. You receive the following message: Address generation for [SMTP] has been enabled for all newly created Recipients. Do you want to automatically add this Address Type to all existing Recipient e-mail addresses? Click Yes if you want to generate this SMTP addresses for existing users. Otherwise, click No to give only newly created users this address. NOTE: You may not want every user to have the secondary e-mail address. If you click No, you must create another recipient policy for those specific users who need this addresses, or manually add the address for each user.
12.	Restart the Microsoft Exchange information store service.