Getting Windows Mobile to Work with Exchange 2007 Using POP3/IMAP4 and SMTP (Part 1)

This is the first of a two-part article that describes how to enable Windows Mobile devices to receive email from Exchange 2007 using IMAP4 and send email using SMTP.

As you probably know, Windows Mobile can only have one connection agreement with Exchange at a time. That means that if you want to access additional email accounts you must use POP3 or IMAP4 for incoming email and SMTP for outgoing email on your device.

In part 1, I will describe how to set up IMAP4 and SMTP client email submission in Exchange 2007. Part 2 will describe how to configure the Windows Mobile client.

Configuring IMAP4 in Exchange 2007
POP3 offers simple email retrieval services from a user's Inbox in Exchange. IMAP4 offers a few more extensive features, including access to all the folders in the user's mailbox. Neither of these services are enabled in Exchange 2007 by default. To enable POP3 or IMAP4 (usually one or the other), simply change the appropriate service from Manual to Automatic on your Exchange 2007 Client Access server (CAS) and then start it. In this article I will be using IMAP4 for Windows Mobile access.

The next step is to configure the logon authentication mechanism for IMAP4. I strongly recommend using TLS to secure logons so that usernames and passwords are not transmitted in plain text.

• Open the Exchange Management Console (EMC)
• Navigate to Server Configuration, Client Access and view the POP3 and IMAP4 properties of the CAS
• Double-click the IMAP4 protocol and select the Authentication tab
• Select Secure Logon. A TLS connection is required for the client to authenticate to the server.
• Select the appropriate X.509 certificate to use and click OK to close the properties window

Configuring SMTP Client Submissions in Exchange 2007
Now we need to configure the Exchange 2007 Hub Transport (HT) server to accept (receive)inbound SMTP connections from clients.

• Open the Exchange Management Console (EMC)
• Navigate to Server Configuration, Hub Transport and select the HT server
• Click New Receive Connector from the Action pane
• Give the new Receive Connector a name such as, "Mobile Clients"
• Select Client as the intended use for this receive connector and click Next
• Click Next to allow all remote networks to use this receive connector
• Click New to create the new Receive Connector
• Now open the properties of the Mobile Clients connector
• Click the Network tab and notice that the port the connector uses is 587
• Click the Authentication tab. Ensure that Transport Layer Security (TLS), Basic Authentication, Offer basic authentication only after starting TLS, and Integrated Windows Authentication are checked.
• Click the Permissions Groups tab. Ensure that only Exchange users is checked and click OK to close the properties window.

Name Resolution and Port Forwarding
The FQDN of the CAS (i.e., cas.mydomain.com) and the HT server (i.e., smtp.mydomain.com) must be resolvable from your Windows Mobile device on the Internet. The CAS must also accept IMAP4 requests and the HT must accept SMTP submissions from your Windows Mobile device. This may require you to configure port forwarding from your external firewall. You will need to forward TCP port 143 for IMAP4 to the CAS and port 587 for client SMTP message submission to the HT server.

Port 25 is fast becoming the port used exclusively for server to server SMTP traffic and port 587 is becoming the standard for client to server SMTP traffic.

So far, we have configured Exchange 2007 to allow secure IMAP4 and SMTP client access. In part 2 of this series I will discuss how to enable IMAP4 and SMTP access to Exchange from a Windows Mobile device.