diff --git a/akka-actor/src/main/scala/akka/actor/Stash.scala b/akka-actor/src/main/scala/akka/actor/Stash.scala
index 106e2eab4c..51428440fd 100644
--- a/akka-actor/src/main/scala/akka/actor/Stash.scala
+++ b/akka-actor/src/main/scala/akka/actor/Stash.scala
@@ -74,8 +74,11 @@ An (unbounded) deque-based mailbox can be configured as follows:
    *  Prepends all messages in the stash to the mailbox, and then clears the stash.
    */
   def unstashAll(): Unit = {
-    theStash.reverseIterator foreach mailbox.queue.addFirst
-    theStash = Vector.empty[Envelope]
+    try {
+      mailbox.enqueueAllFirst(self, theStash.reverseIterator, theStash.size)
+    } finally {
+      theStash = Vector.empty[Envelope]
+    }
   }
 
   /**
diff --git a/akka-actor/src/main/scala/akka/dispatch/Mailbox.scala b/akka-actor/src/main/scala/akka/dispatch/Mailbox.scala
index 1c95843977..281bf9ef09 100644
--- a/akka-actor/src/main/scala/akka/dispatch/Mailbox.scala
+++ b/akka-actor/src/main/scala/akka/dispatch/Mailbox.scala
@@ -318,8 +318,77 @@ trait QueueBasedMessageQueue extends MessageQueue {
   final def hasMessages = !queue.isEmpty
 }
 
+trait UnboundedDequeBasedMessageQueueSemantics extends DequeBasedMessageQueue {
+  final def enqueue(receiver: ActorRef, handle: Envelope): Unit = queue add handle
+
+  final def enqueueFirst(receiver: ActorRef, handle: Envelope): Unit = queue addFirst handle
+
+  final def enqueueAllFirst(receiver: ActorRef, handleIterator: Iterator[Envelope], size: Int) =
+    handleIterator foreach { enqueueFirst(receiver, _) }
+
+  final def dequeue(): Envelope = queue.poll()
+}
+
+trait BoundedDequeBasedMessageQueueSemantics extends DequeBasedMessageQueue {
+  import java.util.concurrent.locks.ReentrantLock
+
+  /* used to enable atomic all-or-nothing enqueueAllFirst in the presence of potential
+   * capacity violations
+   */
+  private val lock = new ReentrantLock(false)
+
+  def pushTimeOut: Duration
+  override def queue: BlockingDeque[Envelope]
+
+  final def enqueue(receiver: ActorRef, handle: Envelope) {
+    lock.lock()
+    try {
+      if (pushTimeOut.length > 0) {
+        queue.offer(handle, pushTimeOut.length, pushTimeOut.unit) || {
+          throw new MessageQueueAppendFailedException("Couldn't enqueue message " + handle + " to " + receiver)
+        }
+      } else queue put handle
+    } finally {
+      lock.unlock()
+    }
+  }
+
+  final def enqueueFirst(receiver: ActorRef, handle: Envelope) {
+    lock.lock()
+    try {
+      if (pushTimeOut.length > 0) {
+        queue.offerFirst(handle, pushTimeOut.length, pushTimeOut.unit) || {
+          throw new MessageQueueAppendFailedException("Couldn't enqueue message " + handle + " to " + receiver)
+        }
+      } else queue putFirst handle
+    } finally {
+      lock.unlock()
+    }
+  }
+
+  final def enqueueAllFirst(receiver: ActorRef, handleIterator: Iterator[Envelope], size: Int) {
+    lock.lock()
+    try {
+      handleIterator foreach { enqueueFirst(receiver, _) }
+    } finally {
+      lock.unlock()
+    }
+  }
+
+  final def dequeue(): Envelope = {
+    lock.lock()
+    try {
+      queue.poll()
+    } finally {
+      lock.unlock()
+    }
+  }
+}
+
 trait DequeBasedMessageQueue extends QueueBasedMessageQueue {
   def queue: Deque[Envelope]
+  def enqueueFirst(receiver: ActorRef, handle: Envelope): Unit
+  def enqueueAllFirst(receiver: ActorRef, handleIterator: Iterator[Envelope], size: Int): Unit
 }
 
 /**
@@ -339,13 +408,6 @@ case class UnboundedMailbox() extends MailboxType {
     }
 }
 
-case class UnboundedDequeBasedMailbox(config: Config) extends MailboxType {
-  final override def create(receiver: ActorContext): Mailbox =
-    new Mailbox(receiver.asInstanceOf[ActorCell]) with DequeBasedMessageQueue with UnboundedMessageQueueSemantics with DefaultSystemMessageQueue {
-      final val queue = new LinkedBlockingDeque[Envelope]()
-    }
-}
-
 case class BoundedMailbox( final val capacity: Int, final val pushTimeOut: Duration) extends MailboxType {
 
   if (capacity < 0) throw new IllegalArgumentException("The capacity for BoundedMailbox can not be negative")
@@ -377,3 +439,21 @@ case class BoundedPriorityMailbox( final val cmp: Comparator[Envelope], final va
     }
 }
 
+case class UnboundedDequeBasedMailbox(config: Config) extends MailboxType {
+  final override def create(receiver: ActorContext): Mailbox =
+    new Mailbox(receiver.asInstanceOf[ActorCell]) with DequeBasedMessageQueue with UnboundedDequeBasedMessageQueueSemantics with DefaultSystemMessageQueue {
+      final val queue = new LinkedBlockingDeque[Envelope]()
+    }
+}
+
+case class BoundedDequeBasedMailbox( final val capacity: Int, final val pushTimeOut: Duration) extends MailboxType {
+
+  if (capacity < 0) throw new IllegalArgumentException("The capacity for BoundedMailbox can not be negative")
+  if (pushTimeOut eq null) throw new IllegalArgumentException("The push time-out for BoundedMailbox can not be null")
+
+  final override def create(receiver: ActorContext): Mailbox =
+    new Mailbox(receiver.asInstanceOf[ActorCell]) with DequeBasedMessageQueue with BoundedDequeBasedMessageQueueSemantics with DefaultSystemMessageQueue {
+      final val queue = new LinkedBlockingDeque[Envelope](capacity)
+      final val pushTimeOut = BoundedDequeBasedMailbox.this.pushTimeOut
+    }
+}