I installed GNU Social over XAMPP on Windows.

But in the last page of the installation it show me the next Warning:

Warning: mail() [function.mail]: Failed to connect to mailserver at "localhost" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set() in C:\xampp\php\PEAR\Mail\mail.php on line 153

Why you dont use PHPMailer to send emails?

or simply send emails without the SMTP Configuration.

Greetings To You!