A common scenario for Exchange Server administrators is a customer that needs to change their primary email addresses to a new domain name.

For example a company that uses as their email address might be acquired, or merge, or simply be rebranding to another name and wants to use as their email address instead.

The Exchange Server administrator’s task is to:

·         Make the new primary email addresses of begin to work

·         Make the previous email addresses of continue to work

There are two features of Exchange Server 2007/2010 that need to be changed for this to happen.

Accepted Domains

The first feature is the Accepted Domains. This is the feature that tells an Exchange 2007/2010 organization which domain names it will accept mail for, and how to treat that domain name.

Accepted domains can be authoritative (ie, the organization owns the domain name and uses it for mail recipients) or can be a relay domain (ie, the organization will accept the emails but send them elsewhere).

There are a few other options such as shared SMTP namespaces but for the purposes of this scenario we’re just dealing with authoritative domains.

To add a new domain name to the organization launch the Exchange Management Console and navigate to Organization Configuration/Hub Transport. Select the Accepted Domains tab to view the current list of domains.

In the Actions pane click on New Accepted Domain.

Enter a Name and the Accepted Domain itself. The name can really be anything you like but most administrators just make it the same as the domain they are adding.

Click New and then Finish to complete the wizard.

Note that if you have Edge Transport servers deployed in your network they will not receive the updated list of Accepted Domains until the next scheduled synchronization of the Edge Subscription.

Email Address Policies

Now that the new domain as been added as an Accepted Domain the next step is to configure an Email Address Policy.

Email Address Policies determine which SMTP addresses as are assigned to which objects in the organization, such as mailboxes, contacts, and distribution groups. Each organization has at least one Email Address Policy that by default will apply to all mail-enabled objects.

Here we can see mailbox users assigned with email addresses.

In the Exchange Management Console navigate to Organization Configuration/Hub Transport, and then select the Email Address Policies tab.

In this scenario we’ll just modify the default policy for all mail-enabled objects. Right-click the Default Email Address Policy and select Edit. Next to skip past the introduction and conditions, until you reach the Email Addresses part of the policy. Click on the Add button.

The Email address local part is an optional setting. If you do not specify one the Alias is used as the prefix of the email address. If you do specify one you can use the Alias or other combinations such as Firstname.Lastname.

Next type the domain name or click Browse to choose it from the list of Accepted Domains.

Click OK once you have configured the new SMTP email address. Select the newly added SMTP address and click on Set as Reply.

This will change the new address to bold, which means that it is the address that mail will appear to be sent from.  The other email addresses in the policy will allow people to continue to receive email sent to those addresses.

Click Next to continue. Now we can choose when the updated policy will be applied to recipients. Usually this will be immediately, however you can choose not make the changes without applying the policy, or schedule it for a later time.

Click Next, and then click Edit to complete the wizard. Depending on the size of your environment this may take some time to finish applying.

After the new policy has been applied you can see the change by refreshing the list of mailboxes. Notice that the primary SMTP addresses have changed from to

If you look at one recipient you can see that the new primary SMTP address has been applied by the policy, and the previous email address has been retained as well to allow mail sent to that address to continue to be received.

You can see that after these tasks have been completed the organization has had the primary email domain changed to a new one while preserving the existing one at the same time.