Manual:$wgSMTP

Details
For using a direct (authenticated) SMTP server connection, you need to fill an array. Set to false (the default value) to use the built-in PHP mail function.

For example: See Mail::factory for a full description of these settings. (Scroll down to the  parameter.) Warning: This setting requires PEAR's Mail package to be installed (run "pear install MAIL" and "pear install Net_SMTP").

Usage, this usage needs to be confirmed!
This can be used to setup access to your mail server. Say, when you have trouble sending mails you may get strange messages - like this: (sorry for the odd way of formating this, I dont know how to do this right) [User:Asset|Asset] (Speciel:Confirmemail)