If you're wanting to use the local SMTP
service (in IIS) for sending email and you have Smartermail installed
on your dedicated server, you'll need to change the port that the local
SMTP service uses.
From Administrative Tools open up IIS.
Expand the menu tree and right click on the SMTP service and select
Properties. Under the General tab of the SMTP properties, click the
Advanced button, then Edit for the IP address that it's using. Change
the TCP port from 25 to 26. Next, start and stop the SMTP service.
SmarterMail also may need to be restarted.