Flarum\Core\Notification\MailableInterface::getEmailView PHP Method

    public function getEmailView();

 /**
  * @param MailableInterface $blueprint
  * @param User $user
  */
 public function send(MailableInterface $blueprint, User $user)
 {
     $this->mailer->send($blueprint->getEmailView(), compact('blueprint', 'user'), function (Message $message) use($blueprint, $user) {
         $message->to($user->email, $user->username)->subject($blueprint->getEmailSubject());
     });
 }