engelsystem/includes/mailer/users_mailer.php

<?php

/**
 * @param User $user_source
 */
function mail_user_delete($user)
{
    engelsystem_email_to_user(
        $user,
        '[engelsystem] ' . _("Your account has been deleted"),
        _("Your angelsystem account has been deleted. If you have any questions regarding your account deletion, please contact heaven.")
    );
}