src/Leevel/Mail/Mail.php
public function message(Closure $callbacks): IMail
    {
        $this->callbackMessage($callbacks, $this->makeMessage());

        return $this;
    }
public function message(Closure $callbacks): IMail
    {
        $this->callbackMessage($callbacks, $this->makeMessage());

        return $this;
    }
消息回调处理.

@param \Closure $callbacks

@return $this