diff --git a/akka-actor-tests/src/test/scala/akka/dispatch/MailboxConfigSpec.scala b/akka-actor-tests/src/test/scala/akka/dispatch/MailboxConfigSpec.scala
index 0e9a1b20cf..d3dd9e9209 100644
--- a/akka-actor-tests/src/test/scala/akka/dispatch/MailboxConfigSpec.scala
+++ b/akka-actor-tests/src/test/scala/akka/dispatch/MailboxConfigSpec.scala
@@ -1,12 +1,13 @@
 package akka.dispatch
+
 import org.scalatest.{ BeforeAndAfterAll, BeforeAndAfterEach }
 import java.util.concurrent.{ TimeUnit, BlockingQueue }
+import java.util.concurrent.ConcurrentLinkedQueue
 import akka.util._
 import akka.util.duration._
 import akka.testkit.AkkaSpec
 import akka.actor.ActorRef
-import akka.actor.ActorCell
-import java.util.concurrent.ConcurrentLinkedQueue
+import akka.actor.ActorContext
 
 @org.junit.runner.RunWith(classOf[org.scalatest.junit.JUnitRunner])
 abstract class MailboxSpec extends AkkaSpec with BeforeAndAfterAll with BeforeAndAfterEach {
@@ -155,7 +156,7 @@ object CustomMailboxSpec {
     }
     """
 
-  class MyMailbox(owner: ActorCell) extends Mailbox(owner)
+  class MyMailbox(owner: ActorContext) extends CustomMailbox(owner)
     with QueueBasedMessageQueue with UnboundedMessageQueueSemantics with DefaultSystemMessageQueue {
     final val queue = new ConcurrentLinkedQueue[Envelope]()
   }
diff --git a/akka-actor/src/main/scala/akka/dispatch/Mailbox.scala b/akka-actor/src/main/scala/akka/dispatch/Mailbox.scala
index 633898c4e9..9940b16aa3 100644
--- a/akka-actor/src/main/scala/akka/dispatch/Mailbox.scala
+++ b/akka-actor/src/main/scala/akka/dispatch/Mailbox.scala
@@ -12,6 +12,7 @@ import annotation.tailrec
 import akka.event.Logging.Error
 import com.typesafe.config.Config
 import java.lang.reflect.InvocationTargetException
+import akka.actor.ActorContext
 
 class MessageQueueAppendFailedException(message: String, cause: Throwable = null) extends AkkaException(message, cause)
 
@@ -35,7 +36,17 @@ object Mailbox {
   final val debug = false
 }
 
-abstract class Mailbox(val actor: ActorCell) extends MessageQueue with SystemMessageQueue with Runnable {
+/**
+ * Custom mailbox implementations are implemented by extending this class.
+ */
+abstract class CustomMailbox(val actorContext: ActorContext) extends Mailbox(actorContext.asInstanceOf[ActorCell])
+
+/**
+ * Mailbox and InternalMailbox is separated in two classes because ActorCell is needed for implementation,
+ * but can't be exposed to user defined mailbox subclasses.
+ *
+ */
+private[akka] abstract class Mailbox(val actor: ActorCell) extends MessageQueue with SystemMessageQueue with Runnable {
   import Mailbox._
 
   @volatile
@@ -319,15 +330,15 @@ trait QueueBasedMessageQueue extends MessageQueue {
  * Mailbox configuration.
  */
 trait MailboxType {
-  def create(receiver: ActorCell): Mailbox
+  def create(receiver: ActorContext): Mailbox
 }
 
 /**
  * It's a case class for Java (new UnboundedMailbox)
  */
 case class UnboundedMailbox() extends MailboxType {
-  override def create(receiver: ActorCell) =
-    new Mailbox(receiver) with QueueBasedMessageQueue with UnboundedMessageQueueSemantics with DefaultSystemMessageQueue {
+  override def create(receiver: ActorContext) =
+    new Mailbox(receiver.asInstanceOf[ActorCell]) with QueueBasedMessageQueue with UnboundedMessageQueueSemantics with DefaultSystemMessageQueue {
       final val queue = new ConcurrentLinkedQueue[Envelope]()
     }
 }
@@ -337,16 +348,16 @@ case class BoundedMailbox( final val capacity: Int, final val pushTimeOut: Durat
   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")
 
-  override def create(receiver: ActorCell) =
-    new Mailbox(receiver) with QueueBasedMessageQueue with BoundedMessageQueueSemantics with DefaultSystemMessageQueue {
+  override def create(receiver: ActorContext) =
+    new Mailbox(receiver.asInstanceOf[ActorCell]) with QueueBasedMessageQueue with BoundedMessageQueueSemantics with DefaultSystemMessageQueue {
       final val queue = new LinkedBlockingQueue[Envelope](capacity)
       final val pushTimeOut = BoundedMailbox.this.pushTimeOut
     }
 }
 
 case class UnboundedPriorityMailbox( final val cmp: Comparator[Envelope]) extends MailboxType {
-  override def create(receiver: ActorCell) =
-    new Mailbox(receiver) with QueueBasedMessageQueue with UnboundedMessageQueueSemantics with DefaultSystemMessageQueue {
+  override def create(receiver: ActorContext) =
+    new Mailbox(receiver.asInstanceOf[ActorCell]) with QueueBasedMessageQueue with UnboundedMessageQueueSemantics with DefaultSystemMessageQueue {
       final val queue = new PriorityBlockingQueue[Envelope](11, cmp)
     }
 }
@@ -356,8 +367,8 @@ case class BoundedPriorityMailbox( final val cmp: Comparator[Envelope], final va
   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")
 
-  override def create(receiver: ActorCell) =
-    new Mailbox(receiver) with QueueBasedMessageQueue with BoundedMessageQueueSemantics with DefaultSystemMessageQueue {
+  override def create(receiver: ActorContext) =
+    new Mailbox(receiver.asInstanceOf[ActorCell]) with QueueBasedMessageQueue with BoundedMessageQueueSemantics with DefaultSystemMessageQueue {
       final val queue = new BoundedBlockingQueue[Envelope](capacity, new PriorityQueue[Envelope](11, cmp))
       final val pushTimeOut = BoundedPriorityMailbox.this.pushTimeOut
     }
@@ -365,8 +376,8 @@ case class BoundedPriorityMailbox( final val cmp: Comparator[Envelope], final va
 
 class CustomMailboxType(mailboxFQN: String) extends MailboxType {
 
-  def create(receiver: ActorCell): Mailbox = {
-    val constructorSignature = Array[Class[_]](classOf[ActorCell])
+  override def create(receiver: ActorContext): Mailbox = {
+    val constructorSignature = Array[Class[_]](classOf[ActorContext])
     ReflectiveAccess.createInstance[AnyRef](mailboxClass, constructorSignature, Array[AnyRef](receiver)) match {
       case Right(instance) ⇒ instance.asInstanceOf[Mailbox]
       case Left(exception) ⇒
@@ -379,7 +390,7 @@ class CustomMailboxType(mailboxFQN: String) extends MailboxType {
     }
   }
 
-  private def mailboxClass: Class[_] = ReflectiveAccess.getClassFor(mailboxFQN, classOf[ActorCell].getClassLoader) match {
+  private def mailboxClass: Class[_] = ReflectiveAccess.getClassFor(mailboxFQN, classOf[ActorContext].getClassLoader) match {
     case Right(clazz) ⇒ clazz
     case Left(exception) ⇒
       val cause = exception match {
diff --git a/akka-durable-mailboxes/akka-beanstalk-mailbox/src/main/scala/akka/actor/mailbox/BeanstalkBasedMailbox.scala b/akka-durable-mailboxes/akka-beanstalk-mailbox/src/main/scala/akka/actor/mailbox/BeanstalkBasedMailbox.scala
index c680511697..57d7b3e098 100644
--- a/akka-durable-mailboxes/akka-beanstalk-mailbox/src/main/scala/akka/actor/mailbox/BeanstalkBasedMailbox.scala
+++ b/akka-durable-mailboxes/akka-beanstalk-mailbox/src/main/scala/akka/actor/mailbox/BeanstalkBasedMailbox.scala
@@ -9,7 +9,7 @@ import java.util.concurrent.TimeUnit.MILLISECONDS
 import akka.actor.LocalActorRef
 import akka.util.Duration
 import akka.AkkaException
-import akka.actor.ActorCell
+import akka.actor.ActorContext
 import akka.dispatch.Envelope
 import akka.event.Logging
 import akka.actor.ActorRef
@@ -19,7 +19,7 @@ class BeanstalkBasedMailboxException(message: String) extends AkkaException(mess
 /**
  * @author <a href="http://jonasboner.com">Jonas Bon&#233;r</a>
  */
-class BeanstalkBasedMailbox(val owner: ActorCell) extends DurableMailbox(owner) with DurableMessageSerialization {
+class BeanstalkBasedMailbox(val owner: ActorContext) extends DurableMailbox(owner) with DurableMessageSerialization {
 
   private val settings = BeanstalkBasedMailboxExtension(owner.system)
   private val messageSubmitDelaySeconds = settings.MessageSubmitDelay.toSeconds.toInt
@@ -78,7 +78,7 @@ class BeanstalkBasedMailbox(val owner: ActorCell) extends DurableMailbox(owner)
     // TODO PN: Why volatile on local variable?
     @volatile
     var connected = false
-    // TODO PN: attempts is not used. Should we have maxAttempts check? Note that this is called from ThreadLocal.initialValue 
+    // TODO PN: attempts is not used. Should we have maxAttempts check? Note that this is called from ThreadLocal.initialValue
     var attempts = 0
     var client: Client = null
     while (!connected) {
diff --git a/akka-durable-mailboxes/akka-file-mailbox/src/main/scala/akka/actor/mailbox/FiledBasedMailbox.scala b/akka-durable-mailboxes/akka-file-mailbox/src/main/scala/akka/actor/mailbox/FiledBasedMailbox.scala
index 8fa7f81e25..55c96ea65c 100644
--- a/akka-durable-mailboxes/akka-file-mailbox/src/main/scala/akka/actor/mailbox/FiledBasedMailbox.scala
+++ b/akka-durable-mailboxes/akka-file-mailbox/src/main/scala/akka/actor/mailbox/FiledBasedMailbox.scala
@@ -5,12 +5,12 @@
 package akka.actor.mailbox
 
 import org.apache.commons.io.FileUtils
-import akka.actor.ActorCell
+import akka.actor.ActorContext
 import akka.dispatch.Envelope
 import akka.event.Logging
 import akka.actor.ActorRef
 
-class FileBasedMailbox(val owner: ActorCell) extends DurableMailbox(owner) with DurableMessageSerialization {
+class FileBasedMailbox(val owner: ActorContext) extends DurableMailbox(owner) with DurableMessageSerialization {
 
   val log = Logging(system, "FileBasedMailbox")
 
diff --git a/akka-durable-mailboxes/akka-mailboxes-common/src/main/scala/akka/actor/mailbox/DurableMailbox.scala b/akka-durable-mailboxes/akka-mailboxes-common/src/main/scala/akka/actor/mailbox/DurableMailbox.scala
index 2c5fd7cb88..aa27a731e5 100644
--- a/akka-durable-mailboxes/akka-mailboxes-common/src/main/scala/akka/actor/mailbox/DurableMailbox.scala
+++ b/akka-durable-mailboxes/akka-mailboxes-common/src/main/scala/akka/actor/mailbox/DurableMailbox.scala
@@ -6,13 +6,13 @@ package akka.actor.mailbox
 import akka.util.ReflectiveAccess
 import java.lang.reflect.InvocationTargetException
 import akka.AkkaException
-import akka.actor.ActorCell
+import akka.actor.ActorContext
 import akka.actor.ActorRef
 import akka.actor.SerializedActorRef
 import akka.dispatch.Envelope
 import akka.dispatch.DefaultSystemMessageQueue
 import akka.dispatch.Dispatcher
-import akka.dispatch.Mailbox
+import akka.dispatch.CustomMailbox
 import akka.dispatch.MailboxType
 import akka.dispatch.MessageDispatcher
 import akka.dispatch.MessageQueue
@@ -34,7 +34,7 @@ class DurableMailboxException private[akka] (message: String, cause: Throwable)
   def this(message: String) = this(message, null)
 }
 
-abstract class DurableMailbox(owner: ActorCell) extends Mailbox(owner) with DefaultSystemMessageQueue {
+abstract class DurableMailbox(owner: ActorContext) extends CustomMailbox(owner) with DefaultSystemMessageQueue {
   import DurableExecutableMailboxConfig._
 
   def system = owner.system
@@ -46,7 +46,7 @@ abstract class DurableMailbox(owner: ActorCell) extends Mailbox(owner) with Defa
 
 trait DurableMessageSerialization {
 
-  def owner: ActorCell
+  def owner: ActorContext
 
   def serialize(durableMessage: Envelope): Array[Byte] = {
 
diff --git a/akka-durable-mailboxes/akka-mongo-mailbox/src/main/scala/akka/actor/mailbox/MongoBasedMailbox.scala b/akka-durable-mailboxes/akka-mongo-mailbox/src/main/scala/akka/actor/mailbox/MongoBasedMailbox.scala
index 6e1c28219d..b404e3c844 100644
--- a/akka-durable-mailboxes/akka-mongo-mailbox/src/main/scala/akka/actor/mailbox/MongoBasedMailbox.scala
+++ b/akka-durable-mailboxes/akka-mongo-mailbox/src/main/scala/akka/actor/mailbox/MongoBasedMailbox.scala
@@ -7,7 +7,7 @@ import akka.AkkaException
 import com.mongodb.async._
 import com.mongodb.async.futures.RequestFutures
 import org.bson.collection._
-import akka.actor.ActorCell
+import akka.actor.ActorContext
 import akka.event.Logging
 import akka.actor.ActorRef
 import akka.dispatch.{ Await, Promise, Envelope, DefaultPromise }
@@ -26,7 +26,7 @@ class MongoBasedMailboxException(message: String) extends AkkaException(message)
  *
  * @author <a href="http://evilmonkeylabs.com">Brendan W. McAdams</a>
  */
-class MongoBasedMailbox(val owner: ActorCell) extends DurableMailbox(owner) {
+class MongoBasedMailbox(val owner: ActorContext) extends DurableMailbox(owner) {
   // this implicit object provides the context for reading/writing things as MongoDurableMessage
   implicit val mailboxBSONSer = new BSONSerializableMailbox(system)
   implicit val safeWrite = WriteConcern.Safe // TODO - Replica Safe when appropriate!
diff --git a/akka-durable-mailboxes/akka-redis-mailbox/src/main/scala/akka/actor/mailbox/RedisBasedMailbox.scala b/akka-durable-mailboxes/akka-redis-mailbox/src/main/scala/akka/actor/mailbox/RedisBasedMailbox.scala
index f937be09e0..21c5555590 100644
--- a/akka-durable-mailboxes/akka-redis-mailbox/src/main/scala/akka/actor/mailbox/RedisBasedMailbox.scala
+++ b/akka-durable-mailboxes/akka-redis-mailbox/src/main/scala/akka/actor/mailbox/RedisBasedMailbox.scala
@@ -6,14 +6,14 @@ package akka.actor.mailbox
 import com.redis._
 import akka.actor.LocalActorRef
 import akka.AkkaException
-import akka.actor.ActorCell
+import akka.actor.ActorContext
 import akka.dispatch.Envelope
 import akka.event.Logging
 import akka.actor.ActorRef
 
 class RedisBasedMailboxException(message: String) extends AkkaException(message)
 
-class RedisBasedMailbox(val owner: ActorCell) extends DurableMailbox(owner) with DurableMessageSerialization {
+class RedisBasedMailbox(val owner: ActorContext) extends DurableMailbox(owner) with DurableMessageSerialization {
 
   private val settings = RedisBasedMailboxExtension(owner.system)
 
diff --git a/akka-durable-mailboxes/akka-zookeeper-mailbox/src/main/scala/akka/actor/mailbox/ZooKeeperBasedMailbox.scala b/akka-durable-mailboxes/akka-zookeeper-mailbox/src/main/scala/akka/actor/mailbox/ZooKeeperBasedMailbox.scala
index 3a50b93e93..1cdedba25d 100644
--- a/akka-durable-mailboxes/akka-zookeeper-mailbox/src/main/scala/akka/actor/mailbox/ZooKeeperBasedMailbox.scala
+++ b/akka-durable-mailboxes/akka-zookeeper-mailbox/src/main/scala/akka/actor/mailbox/ZooKeeperBasedMailbox.scala
@@ -8,7 +8,7 @@ import akka.actor.LocalActorRef
 import akka.util.Duration
 import akka.AkkaException
 import org.I0Itec.zkclient.serialize._
-import akka.actor.ActorCell
+import akka.actor.ActorContext
 import akka.cluster.zookeeper.AkkaZkClient
 import akka.dispatch.Envelope
 import akka.event.Logging
@@ -17,7 +17,7 @@ import akka.actor.ActorRef
 
 class ZooKeeperBasedMailboxException(message: String) extends AkkaException(message)
 
-class ZooKeeperBasedMailbox(val owner: ActorCell) extends DurableMailbox(owner) with DurableMessageSerialization {
+class ZooKeeperBasedMailbox(val owner: ActorContext) extends DurableMailbox(owner) with DurableMessageSerialization {
 
   private val settings = ZooKeeperBasedMailboxExtension(owner.system)
   val queueNode = "/queues"