there is no email functionality in PowerCMS2.
No email will be sent when a new user is added. This will only occur in in the User Registration Solution Pack, or PowerStore.
For either of those solutions, look in the WA_UniversalEmail folder.
for each email that can be sent out, there will be a php file using the following naming convention:
WAUE_<page name>_<number>.php
open each one, and look for a line similar to:
$WA_MailObject = WAUE_Definition("".($WAGLOBAL_Email_Server) ."","25","","","","");
change the "25" to the correct port to use:
$WA_MailObject = WAUE_Definition("".($WAGLOBAL_Email_Server) ."","587","","","","");