How can i discover the PHP code that transmits the e-mail towards the user? I wish to add the username &lifier e-mail during my e-newsletter database and that i aren't able to find the code that transmits the e-mail to include my query there.

Thanks greatly!

You should use PHP mail function : http://php.net/manual/en/function.mail.php

Point your contact form's action towards the PHP script, then add validation, send mail or save info to database.