newbie: mail setup in php.ini

Hi all, I have a simple form that seems to do everything except send the mail and it's not even returing TRUE from mail() anymore. I'm pretty sure there's a problem with our smtp server since we're using our ISP's smtp to send mail from usually so I've tried setting SMTP to that outside server in the php.ini but should it be the IP address or what? This is the error I'm getting: Warning: Failed to Connect in D:\Cryptic\pages\forms\contact_form.php Thanks for your help, Mat