diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/controllers/MessageController.java b/service/src/main/java/org/whispersystems/textsecuregcm/controllers/MessageController.java
index 3d1f39589..c66d4a7e5 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/controllers/MessageController.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/controllers/MessageController.java
@@ -16,6 +16,7 @@
  */
 package org.whispersystems.textsecuregcm.controllers;
 
+import com.codahale.metrics.Histogram;
 import com.codahale.metrics.Meter;
 import com.codahale.metrics.MetricRegistry;
 import com.codahale.metrics.SharedMetricRegistries;
@@ -79,11 +80,12 @@ import static com.codahale.metrics.MetricRegistry.name;
 @Path("/v1/messages")
 public class MessageController {
 
-  private final Logger         logger                       = LoggerFactory.getLogger(MessageController.class);
-  private final MetricRegistry metricRegistry               = SharedMetricRegistries.getOrCreate(Constants.METRICS_NAME);
-  private final Meter          unidentifiedMeter            = metricRegistry.meter(name(getClass(), "delivery", "unidentified"));
-  private final Meter          identifiedMeter              = metricRegistry.meter(name(getClass(), "delivery", "identified"  ));
-  private final Timer          sendMessageInternalTimer     = metricRegistry.timer(name(getClass(), "sendMessageInternal"));
+  private final Logger         logger                           = LoggerFactory.getLogger(MessageController.class);
+  private final MetricRegistry metricRegistry                   = SharedMetricRegistries.getOrCreate(Constants.METRICS_NAME);
+  private final Meter          unidentifiedMeter                = metricRegistry.meter(name(getClass(), "delivery", "unidentified"));
+  private final Meter          identifiedMeter                  = metricRegistry.meter(name(getClass(), "delivery", "identified"  ));
+  private final Timer          sendMessageInternalTimer         = metricRegistry.timer(name(getClass(), "sendMessageInternal"));
+  private final Histogram      outgoingMessageListSizeHistogram = metricRegistry.histogram(name(getClass(), "outgoingMessageListSize"));
 
   private final RateLimiters           rateLimiters;
   private final PushSender             pushSender;
@@ -188,10 +190,14 @@ public class MessageController {
       RedisOperation.unchecked(() -> apnFallbackManager.cancel(account, account.getAuthenticatedDevice().get()));
     }
 
-    return messagesManager.getMessagesForDevice(account.getNumber(),
-                                                account.getUuid(),
-                                                account.getAuthenticatedDevice().get().getId(),
-                                                userAgent);
+    final OutgoingMessageEntityList outgoingMessages = messagesManager.getMessagesForDevice(account.getNumber(),
+                                                                                            account.getUuid(),
+                                                                                            account.getAuthenticatedDevice().get().getId(),
+                                                                                            userAgent);
+
+    outgoingMessageListSizeHistogram.update(outgoingMessages.getMessages().size());
+
+    return outgoingMessages;
   }
 
   @Timed