How to change SMTP port 25 to another port in Exchange 2000 and in Exchange 2003 (274842)


The information in this article applies to:

  • Microsoft Exchange Server 2003 Enterprise Edition
  • Microsoft Exchange Server 2003 Standard Edition
  • Microsoft Exchange 2000 Server
This article was previously published under Q274842

SUMMARY

This article explains how to change Simple Mail Transport Protocol (SMTP) port 25 to another port in Microsoft Exchange 2000 Server and in Microsoft Exchange Server 2003.

Because SMTP is now the default protocol that Exchange 2000 and Exchange 2003 use to communicate between Exchange-based servers within one site or between a server and the Internet, if you change the port that is used to listen to SMTP traffic, you may experience wide-ranging and unexpected negative effects. When you change the default port configuration, you should carefully consider and test the configuration before you implement it in a production environment.

MORE INFORMATION

How to Change the SMTP Listening Port

To change the SMTP listening port on a server that is running Exchange 2000 or Exchange 2003 from port 25 to another port, for example, port 26, follow these steps:
  1. Start the Exchange System Manager.
  2. Locate and click Servername, click Protocols, and then click SMTP.
  3. Right-click the Default SMTP Virtual Server object, and then click Properties.
  4. On the General tab, click the Advanced button, click the Edit button, and then set the Transmission Control Protocol (TCP) port to 26 (or whatever new value you require).
This method sets the port that this virtual server listens to for SMTP traffic.

Warning If you change this port number, the virtual server will not be reachable by other SMTP virtual servers that are configured to have the default (Outgoing) SMTP port 25.

How to Change the Outbound TCP Port

NOTE: Every remote SMTP server that you want to communicate with must be configured to accept connections on the specified port. In most cases, you do not want to change the default port setting.

To change the outbound TCP port, follow these steps:
  1. Start the Exchange System Manager.
  2. Locate and click Servername, click Protocols, and then click SMTP.
  3. Right-click the Default SMTP Virtual Server object, and then click Properties.
  4. Click the Delivery tab, and click the Outbound connections button. Set the TCP port to 26 (or whatever value you require).
  5. Quit the Exchange System Manager for the changes to take place.
All outbound SMTP traffic is now sent to port 26 on other servers.

NOTE: For these steps, the Display routing groups check box is enabled on the Exchange Organization Name properties in a mixed mode site.
Modification Type:MajorLast Reviewed:2/10/2006
Keywords:kbhowto KB274842
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