I needed to change the port for outgoing emails on on of our SBS 2003 server to 587 as the new host doesn’t use port 25 for outgoing emails, at first i thought this might be set in the SMTP connector but that is not correct.
The listening port and outbound TCP port are actually located under SMTP protocols in Exchange System manager.
I got all this information from Microsoft KB274842
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:
Start the Exchange System Manager.
Locate and click Servername, click Protocols, and then click SMTP.
Right-click the Default SMTP Virtual Server object, and then click Properties.
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:
Start the Exchange System Manager.
Locate and click Servername, click Protocols, and then click SMTP.
Right-click the Default SMTP Virtual Server object, and then click Properties.
Click the Delivery tab, and click the Outbound connections button. Set the TCP port to 26 (or whatever value you require).
Quit the Exchange System Manager for the changes to take place.
All outbound SMTP traffic is now sent to port 26 on other servers.