allow customization of mail message building

src/Illuminate/Auth/Notifications/ResetPassword.php

@@ -14,6 +14,13 @@ class ResetPassword extends Notification
      */
     public $token;
 
+    /**
+     * The callback that should be used to build the mail message.
+     *
+     * @var \Closure|null
+     */
+    public static $toMailCallback;
+
     /**
      * Create a notification instance.
      *
@@ -44,9 +51,24 @@ public function via($notifiable)
      */
     public function toMail($notifiable)
     {
+        if (static::$toMailCallback) {
+            return call_user_func(static::$toMailCallback, $notifiable, $this->token);
+        }
+
         return (new MailMessage)
             ->line('You are receiving this email because we received a password reset request for your account.')
             ->action('Reset Password', url(config('app.url').route('password.reset', $this->token, false)))
             ->line('If you did not request a password reset, no further action is required.');
     }
+
+    /**
+     * Set a callback that should be used when building the notification mail message.
+     *
+     * @param  \Closure  $callback
+     * @return void
+     */
+    public static function toMailUsing($callback)
+    {
+        static::$toMailCallback = $callback;
+    }
 }