An example of the ClientAdd WHMCS hook for Brandon

hook.php

<?php
 
 function send_invitiation_email($vars) {
 
	$command = "sendemail";
	$adminuser = "secret";
	$values["messagename"] = "Google Groups Invitation";
	$values["id"] =  $vars['userid'];
	$results = localAPI($command, $values, $adminuser);

	// auto-invite to announcements list
	$to = "[email protected]";
	$subject = "Add me to the mailing list!";
	$message = "Hello! Please add me to the announcements mailing list.";
	$from = $vars['email'];
	$headers = "From:" . $from;
	mail($to, $subject, $message, $headers);
	
 }
 
 // more documentation: http://docs.whmcs.com/Hooks:ClientAdd
 add_hook("ClientAdd", 1, "send_invitiation_email");
 
 ?>