title: Akka sender reference contains dead letters
body: <pre><code>object SenderTest extends App {
    val s = ActorSystem("test")
    val ar = s.actorOf(Props[A], "Aactor")
    ar ! "abc"
  }
  
  class A extends Actor {
    val sender_ = sender()
    override def receive: Receive = {
      case _: String =&gt; {
        println("inside A receive block")
        val b = context.actorOf(Props[B], "Bactor")
        b ! 12
      }
    }
  }
  
  class B extends Actor {
    val sender_ = sender()
    override def receive: Receive = {
      case _: Int =&gt; {
        println(sender_)
        println("inside B receive block")
        sender_ ! 22
      }
    }
  }
  </code></pre>
  
  <p>I was expecting <code>println(sender_)</code> to print actor <code>A</code> information, but it's printing dead letters. As it's called from actor <code>A</code>, I don't understand why it's printing dead letters. How do I modify this so that I can get the sender's reference?</p>