Recently I had to change the outbound SMTP connection port for my alerts on a vCenter server. The default is 25 but my customer had their Exchange 2007 relay configured for 2525.

Here’s how to do it:

1. Connect to the vCenter server with your client
2. Select Administration -> vCenter Server Settings
3. At the bottom of the left column select Advanced Settings
4. Find the value mail.smtp.port, click on 25 and type in the new value