diff --git a/src/main/java/io/vlingo/xoom/actors/ResumingMailbox.java b/src/main/java/io/vlingo/xoom/actors/ResumingMailbox.java
deleted file mode 100644
index 294c69d0..00000000
--- a/src/main/java/io/vlingo/xoom/actors/ResumingMailbox.java
+++ /dev/null
@@ -1,51 +0,0 @@
-// Copyright © 2012-2021 VLINGO LABS. All rights reserved.
-//
-// This Source Code Form is subject to the terms of the
-// Mozilla Public License, v. 2.0. If a copy of the MPL
-// was not distributed with this file, You can obtain
-// one at https://mozilla.org/MPL/2.0/.
-
-package io.vlingo.xoom.actors;
-
-public class ResumingMailbox implements Mailbox {
-  private final Message message;
-
-  public ResumingMailbox(final Message message) {
-    this.message = message;
-  }
-
-  @Override
-  public void run() {
-    message.deliver();
-  }
-
-  @Override
-  public void close() { }
-
-  @Override
-  public boolean isClosed() { return false; }
-
-  @Override
-  public boolean isDelivering() { return true; }
-
-  @Override
-  public int concurrencyCapacity() { return 0; }
-
-  @Override
-  public void resume(final String name) { }
-
-  @Override
-  public void send(final Message message) { }
-
-  @Override
-  public void suspendExceptFor(String name, Class<?>... overrides) { }
-
-  @Override
-  public boolean isSuspended() { return false; }
-
-  @Override
-  public Message receive() { return null; }
-
-  @Override
-  public int pendingMessages() { return 1; }
-}
diff --git a/src/main/java/io/vlingo/xoom/actors/plugin/mailbox/concurrentqueue/ConcurrentQueueMailbox.java b/src/main/java/io/vlingo/xoom/actors/plugin/mailbox/concurrentqueue/ConcurrentQueueMailbox.java
index aeb47c6b..e7731aeb 100644
--- a/src/main/java/io/vlingo/xoom/actors/plugin/mailbox/concurrentqueue/ConcurrentQueueMailbox.java
+++ b/src/main/java/io/vlingo/xoom/actors/plugin/mailbox/concurrentqueue/ConcurrentQueueMailbox.java
@@ -10,25 +10,26 @@
 import io.vlingo.xoom.actors.Dispatcher;
 import io.vlingo.xoom.actors.Mailbox;
 import io.vlingo.xoom.actors.Message;
-import io.vlingo.xoom.actors.ResumingMailbox;
 
 import java.util.*;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
 public class ConcurrentQueueMailbox implements Mailbox, Runnable {
   private AtomicBoolean delivering;
   private final Dispatcher dispatcher;
-  private AtomicReference<SuspendedDeliveryOverrides> suspendedDeliveryOverrides;
-  private AtomicReference<SuspendedDeliveryQueue> suspendedDeliveryQueue;
+  private final AtomicReference<SuspendedDeliveryOverrides> suspendedDeliveryOverrides;
+  private final AtomicReference<SuspendedDeliveryQueue> suspendedDeliveryQueue;
   private final Queue<Message> queue;
   private final byte throttlingCount;
 
   @Override
   public void close() {
     queue.clear();
+    suspendedDeliveryQueue.get().clear();
   }
 
   @Override
@@ -44,6 +45,7 @@ public int concurrencyCapacity() {
   @Override
   public void resume(final String name) {
     if (suspendedDeliveryOverrides.get().pop(name)) {
+      suspendedDeliveryQueue.get().putBack(this::queue);
       dispatcher.execute(this);
     }
   }
@@ -112,7 +114,7 @@ public void run() {
   /* @see io.vlingo.xoom.actors.Mailbox#pendingMessages() */
   @Override
   public int pendingMessages() {
-    return queue.size();
+    return queue.size() + suspendedDeliveryQueue.get().size();
   }
 
   private void queue(final Message message) {
@@ -279,7 +281,6 @@ public void add(final Message message) {
           break;
         }
       }
-
     }
 
     public Message poll() {
@@ -295,8 +296,32 @@ public Message poll() {
       }
     }
 
+    public void putBack(final Consumer<Message> consumer) {
+      while(true) {
+        if (accessible.compareAndSet(false, true)) {
+          queue.forEach(consumer);
+          queue.clear();
+          accessible.set(false);
+          break;
+        }
+      }
+    }
+
+    public void clear() {
+      while(true) {
+        if (accessible.compareAndSet(false, true)) {
+          queue.clear();
+          break;
+        }
+      }
+    }
+
     public boolean isEmpty() {
       return queue.isEmpty();
     }
+
+    public int size() {
+      return queue.size();
+    }
   }
 }
diff --git a/src/test/java/io/vlingo/xoom/actors/plugin/mailbox/concurrentqueue/ConcurrentQueueMailboxTest.java b/src/test/java/io/vlingo/xoom/actors/plugin/mailbox/concurrentqueue/ConcurrentQueueMailboxTest.java
index abc2df39..037cca06 100644
--- a/src/test/java/io/vlingo/xoom/actors/plugin/mailbox/concurrentqueue/ConcurrentQueueMailboxTest.java
+++ b/src/test/java/io/vlingo/xoom/actors/plugin/mailbox/concurrentqueue/ConcurrentQueueMailboxTest.java
@@ -113,6 +113,33 @@ public void testThatSuspendedOverrideMessagesAreDeliveredInOrderTheyArrived() {
     assertEquals(Arrays.asList(0, 1, 2), actor.testResults.getCounts());
   }
 
+  @Test
+  public void testThatSuspendedButNotHandledMessagesAreQueued() {
+
+    final Dispatcher dispatcher = new ExecutorDispatcher(2, 0, 1.0f);
+    final Mailbox mailbox = new ConcurrentQueueMailbox(dispatcher, 1);
+
+    final TestResults testResults = new TestResults(3);
+    final CountTakerActor actor = new CountTakerActor(testResults);
+
+    mailbox.suspendExceptFor("paused#", CountTaker.class);
+
+    for (int count = 0; count < 3; ++count) {
+      final int countParam = count;
+      final SerializableConsumer<CountTaker> consumer = (consumerActor) -> {
+        // Give longer Delay to messages that come first
+        delay(20 - (countParam * 10));
+        consumerActor.take(countParam);
+      };
+      final LocalMessage<CountTaker> message = new LocalMessage<CountTaker>(actor, CountTaker.class, consumer, "take(int)");
+      mailbox.send(message);
+    }
+
+    mailbox.resume("paused#");
+
+    assertEquals(Arrays.asList(0, 1, 2), actor.testResults.getCounts());
+  }
+
   @Before
   @Override
   public void setUp() throws Exception {