XFOR: Exchange and Internet Mail Client Co-existence

Customers want to maintain connectivity and co-existence with both Internet Mail/POP3 and Exchange Server services, but they do not want the users to be able to select Exchange Server users from the global address list (GAL).

For example, users are using Microsoft Outlook 97 as their client. They have two services for each profile: Internet Mail Service and an Exchange Server service. Also, each user has two SMTP aliases: Internet Mail/POP3 system (for example, Adam) and another for Exchange Server (for example Adam.Barr).

To enable this functionality, create alternate recipients for each Exchange Server mailbox, and hide the Exchange Server mailbox, by following these steps:

1. Create a custom recipient (CR) that maps to each user's alias on the POP3 system (for example, a CR whose SMTP address would be Adam@acme.microsoft.com).
2. In the Properties for each native Exchange Server recipient, select the Delivery Options tab, and under Alternate Recipients, click the option button next to the text field, and click Modify. Select the CR you created in Step 1, and click OK.
3. While still in the recipient's Properties, select the Advanced tab, and clear the "Hide from address book" check box. Click OK.

The net effect of this is that the Exchange Server recipients do not appear in the GAL (so they can't be selected from within the organization). Also, any mail accidentally sent to the Exchange Server mailbox gets copied/forwarded to the alternate recipient, which just happens to be the user's POP3 mailbox. Additionally, hiding the Exchange Server mailbox from the address book does not affect inbound routing of messages from other systems.

Now, administrators can migrate users to Exchange Server on a user-by-user basis. As users are migrated, simply remove the CR, unhide the mailbox, and switch "Alternate Recipient" back to "None."

The example companies, organizations, products, people and events depicted herein are fictitious. No association with any real company, organization, product, person or event is intended or should be inferred.