This hook required to be used with additional hook. https://www.opensource-socialnetwork.org/documentation/view/5558/mail-send-policy

~~~
<?php
function my_component_init(){
ossn_add_hook('email', 'send:policy', 'my_component_hook');
ossn_add_hook('email', 'send', 'my_own_mailer');
}
function my_component_hook($hook, $type, $allowed_or_not, $instance){
return false;
}
function my_own_mailer($hook, $type, $send_or_not, $mail){
//$mail contain phpmailer object
//it contains like $mail->Body, $mail->Subject
//you may use these to pass it to your own mail handler.
}
ossn_register_callback('ossn', 'init', 'my_component_init');
~~~