Coexistence While Sharing an SMTP Mail Domain

 

This section explains how to configure Exchange Server and the Windows Server POP3 service to allow users to share a single SMTP e-mail domain. The shared SMTP mail domain is the primary SMTP address of all Exchange Server users. This address is the return address that is shown on all mail destined to external or Internet addresses. Similarly, POP3 users use this same e-mail address when communicating with external users.

The best way to share an SMTP mail domain is to allow Exchange Server to accept incoming mail from the Internet and locate a recipient in the Exchange Server organization, and then forward the mail to users on the Windows Server POP3 service. The following figure illustrates this example.

Sharing an SMTP domain

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In this scenario, Exchange Server functions as the first mail server, and the Exchange server is configured to use the SMTP mail domain of northwindtraders.com. The server running the Windows Server POP3 service is configured with a domain of pop.northwindtraders.com, but POP3 clients are configured to use northwindtraders.com as their return address.

Important

You cannot configure a server running the Windows Server POP3 service that uses the same mail domain as the Exchange Server system. Your server running the Windows Server POP3 service must be configured with a different mail domain.

For detailed steps on how to configure Exchange Server and Windows Server POP3 service to coexist using a single SMTP e-mail domain, see How to Configure Exchange and Windows Server POP3 Service to Coexist Using a Single SMTP Mail Domain.