diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java b/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
index fceb9f9fd..9d3273d0c 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java
@@ -380,7 +380,7 @@ public class WhisperServerService extends Application<WhisperServerConfiguration
     AttachmentControllerV2 attachmentControllerV2    = new AttachmentControllerV2(rateLimiters, config.getAwsAttachmentsConfiguration().getAccessKey(), config.getAwsAttachmentsConfiguration().getAccessSecret(), config.getAwsAttachmentsConfiguration().getRegion(), config.getAwsAttachmentsConfiguration().getBucket());
     AttachmentControllerV3 attachmentControllerV3    = new AttachmentControllerV3(rateLimiters, config.getGcpAttachmentsConfiguration().getDomain(), config.getGcpAttachmentsConfiguration().getEmail(), config.getGcpAttachmentsConfiguration().getMaxSizeInBytes(), config.getGcpAttachmentsConfiguration().getPathPrefix(), config.getGcpAttachmentsConfiguration().getRsaSigningKey());
     KeysController         keysController            = new KeysController(rateLimiters, keys, accountsManager, directoryQueue);
-    MessageController      messageController         = new MessageController(rateLimiters, messageSender, receiptSender, accountsManager, messagesManager, apnFallbackManager);
+    MessageController      messageController         = new MessageController(rateLimiters, messageSender, receiptSender, accountsManager, messagesManager, apnFallbackManager, featureFlagsManager);
     ProfileController      profileController         = new ProfileController(rateLimiters, accountsManager, profilesManager, usernamesManager, cdnS3Client, profileCdnPolicyGenerator, profileCdnPolicySigner, config.getCdnConfiguration().getBucket(), zkProfileOperations, isZkEnabled);
     StickerController      stickerController         = new StickerController(rateLimiters, config.getCdnConfiguration().getAccessKey(), config.getCdnConfiguration().getAccessSecret(), config.getCdnConfiguration().getRegion(), config.getCdnConfiguration().getBucket());
     RemoteConfigController remoteConfigController    = new RemoteConfigController(remoteConfigsManager, config.getRemoteConfigConfiguration().getAuthorizedTokens(), config.getRemoteConfigConfiguration().getGlobalConfig());
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 976a3af70..ecb9dd7d1 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/controllers/MessageController.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/controllers/MessageController.java
@@ -36,6 +36,7 @@ import org.whispersystems.textsecuregcm.redis.RedisOperation;
 import org.whispersystems.textsecuregcm.storage.Account;
 import org.whispersystems.textsecuregcm.storage.AccountsManager;
 import org.whispersystems.textsecuregcm.storage.Device;
+import org.whispersystems.textsecuregcm.storage.FeatureFlagsManager;
 import org.whispersystems.textsecuregcm.storage.MessagesManager;
 import org.whispersystems.textsecuregcm.util.Base64;
 import org.whispersystems.textsecuregcm.util.Constants;
@@ -61,6 +62,7 @@ import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Optional;
+import java.util.Random;
 import java.util.Set;
 import java.util.UUID;
 
@@ -85,6 +87,9 @@ public class MessageController {
   private final MessagesManager        messagesManager;
   private final ApnFallbackManager     apnFallbackManager;
 
+  private final FeatureFlagsManager featureFlagsManager;
+  private final Random random = new Random();
+
   private static final String CONTENT_SIZE_DISTRIBUTION_NAME                     = name(MessageController.class, "messageContentSize");
   private static final String OUTGOING_MESSAGE_LIST_SIZE_BYTES_DISTRIBUTION_NAME = name(MessageController.class, "outgoingMessageListSizeBytes");
 
@@ -95,7 +100,8 @@ public class MessageController {
                            ReceiptSender receiptSender,
                            AccountsManager accountsManager,
                            MessagesManager messagesManager,
-                           ApnFallbackManager apnFallbackManager)
+                           ApnFallbackManager apnFallbackManager,
+                           FeatureFlagsManager featureFlagsManager)
   {
     this.rateLimiters           = rateLimiters;
     this.messageSender          = messageSender;
@@ -103,6 +109,7 @@ public class MessageController {
     this.accountsManager        = accountsManager;
     this.messagesManager        = messagesManager;
     this.apnFallbackManager     = apnFallbackManager;
+    this.featureFlagsManager    = featureFlagsManager;
   }
 
   @Timed
@@ -117,77 +124,105 @@ public class MessageController {
                                          @Valid                                    IncomingMessageList messages)
       throws RateLimitExceededException
   {
-    return Response.status(503).build();
-    /* if (!source.isPresent() && !accessKey.isPresent()) {
-      throw new WebApplicationException(Response.Status.UNAUTHORIZED);
-    }
-
-    if (source.isPresent() && !source.get().isFor(destinationName)) {
-      rateLimiters.getMessagesLimiter().validate(source.get().getNumber() + "__" + destinationName);
-    }
-
-    if (source.isPresent() && !source.get().isFor(destinationName)) {
-      identifiedMeter.mark();
-    } else if (!source.isPresent()) {
-      unidentifiedMeter.mark();
-    }
-
-    for (final IncomingMessage message : messages.getMessages()) {
-      int contentLength = 0;
-
-      if (!Util.isEmpty(message.getContent())) {
-        contentLength += message.getContent().length();
+    if (random.nextDouble() <= getSuccessPercentage()) {
+      if (!source.isPresent() && !accessKey.isPresent()) {
+        throw new WebApplicationException(Response.Status.UNAUTHORIZED);
       }
 
-      if (!Util.isEmpty(message.getBody())) {
-        contentLength += message.getBody().length();
+      if (source.isPresent() && !source.get().isFor(destinationName)) {
+        rateLimiters.getMessagesLimiter().validate(source.get().getNumber() + "__" + destinationName);
       }
 
-      Metrics.summary(CONTENT_SIZE_DISTRIBUTION_NAME, UserAgentTagUtil.getUserAgentTags(userAgent)).record(contentLength);
-
-      if (contentLength > MAX_MESSAGE_SIZE) {
-        // TODO Reject the request
-        rejectOversizeMessageMeter.mark();
+      if (source.isPresent() && !source.get().isFor(destinationName)) {
+        identifiedMeter.mark();
+      } else if (!source.isPresent()) {
+        unidentifiedMeter.mark();
       }
-    }
 
-    try {
-      boolean isSyncMessage = source.isPresent() && source.get().isFor(destinationName);
+      for (final IncomingMessage message : messages.getMessages()) {
+        int contentLength = 0;
 
-      Optional<Account> destination;
+        if (!Util.isEmpty(message.getContent())) {
+          contentLength += message.getContent().length();
+        }
 
-      if (!isSyncMessage) destination = accountsManager.get(destinationName);
-      else                destination = source;
+        if (!Util.isEmpty(message.getBody())) {
+          contentLength += message.getBody().length();
+        }
 
-      OptionalAccess.verify(source, accessKey, destination);
-      assert(destination.isPresent());
+        Metrics.summary(CONTENT_SIZE_DISTRIBUTION_NAME, UserAgentTagUtil.getUserAgentTags(userAgent)).record(contentLength);
 
-      validateCompleteDeviceList(destination.get(), messages.getMessages(), isSyncMessage);
-      validateRegistrationIds(destination.get(), messages.getMessages());
-
-      for (IncomingMessage incomingMessage : messages.getMessages()) {
-        Optional<Device> destinationDevice = destination.get().getDevice(incomingMessage.getDestinationDeviceId());
-
-        if (destinationDevice.isPresent()) {
-          sendMessage(source, destination.get(), destinationDevice.get(), messages.getTimestamp(), messages.isOnline(), incomingMessage);
+        if (contentLength > MAX_MESSAGE_SIZE) {
+          // TODO Reject the request
+          rejectOversizeMessageMeter.mark();
         }
       }
 
-      return new SendMessageResponse(!isSyncMessage && source.isPresent() && source.get().getEnabledDeviceCount() > 1);
-    } catch (NoSuchUserException e) {
-      throw new WebApplicationException(Response.status(404).build());
-    } catch (MismatchedDevicesException e) {
-      throw new WebApplicationException(Response.status(409)
-                                                .type(MediaType.APPLICATION_JSON_TYPE)
-                                                .entity(new MismatchedDevices(e.getMissingDevices(),
-                                                                              e.getExtraDevices()))
-                                                .build());
-    } catch (StaleDevicesException e) {
-      throw new WebApplicationException(Response.status(410)
-                                                .type(MediaType.APPLICATION_JSON)
-                                                .entity(new StaleDevices(e.getStaleDevices()))
-                                                .build());
-    } */
+      try {
+        boolean isSyncMessage = source.isPresent() && source.get().isFor(destinationName);
+
+        Optional<Account> destination;
+
+        if (!isSyncMessage) destination = accountsManager.get(destinationName);
+        else                destination = source;
+
+        OptionalAccess.verify(source, accessKey, destination);
+        assert(destination.isPresent());
+
+        validateCompleteDeviceList(destination.get(), messages.getMessages(), isSyncMessage);
+        validateRegistrationIds(destination.get(), messages.getMessages());
+
+        for (IncomingMessage incomingMessage : messages.getMessages()) {
+          Optional<Device> destinationDevice = destination.get().getDevice(incomingMessage.getDestinationDeviceId());
+
+          if (destinationDevice.isPresent()) {
+            sendMessage(source, destination.get(), destinationDevice.get(), messages.getTimestamp(), messages.isOnline(), incomingMessage);
+          }
+        }
+
+        return Response.ok(new SendMessageResponse(!isSyncMessage && source.isPresent() && source.get().getEnabledDeviceCount() > 1)).build();
+      } catch (NoSuchUserException e) {
+        throw new WebApplicationException(Response.status(404).build());
+      } catch (MismatchedDevicesException e) {
+        throw new WebApplicationException(Response.status(409)
+                .type(MediaType.APPLICATION_JSON_TYPE)
+                .entity(new MismatchedDevices(e.getMissingDevices(),
+                        e.getExtraDevices()))
+                .build());
+      } catch (StaleDevicesException e) {
+        throw new WebApplicationException(Response.status(410)
+                .type(MediaType.APPLICATION_JSON)
+                .entity(new StaleDevices(e.getStaleDevices()))
+                .build());
+      }    } else {
+      return Response.status(503).build();
+    }
+  }
+
+  private double getSuccessPercentage() {
+    if (featureFlagsManager.isFeatureFlagActive("SEND_MESSAGE_1_PERCENT")) {
+      return 0.01;
+    } else if (featureFlagsManager.isFeatureFlagActive("SEND_MESSAGE_2_PERCENT")) {
+      return 0.02;
+    } else if (featureFlagsManager.isFeatureFlagActive("SEND_MESSAGE_4_PERCENT")) {
+      return 0.04;
+    } else if (featureFlagsManager.isFeatureFlagActive("SEND_MESSAGE_8_PERCENT")) {
+      return 0.08;
+    } else if (featureFlagsManager.isFeatureFlagActive("SEND_MESSAGE_16_PERCENT")) {
+      return 0.16;
+    } else if (featureFlagsManager.isFeatureFlagActive("SEND_MESSAGE_32_PERCENT")) {
+      return 0.32;
+    } else if (featureFlagsManager.isFeatureFlagActive("SEND_MESSAGE_48_PERCENT")) {
+      return 0.48;
+    } else if (featureFlagsManager.isFeatureFlagActive("SEND_MESSAGE_64_PERCENT")) {
+      return 0.64;
+    } else if (featureFlagsManager.isFeatureFlagActive("SEND_MESSAGE_80_PERCENT")) {
+      return 0.80;
+    } else if (featureFlagsManager.isFeatureFlagActive("SEND_MESSAGE_100_PERCENT")) {
+      return 1.0d;
+    }
+
+    return 0;
   }
 
   @Timed
diff --git a/service/src/test/java/org/whispersystems/textsecuregcm/tests/controllers/MessageControllerTest.java b/service/src/test/java/org/whispersystems/textsecuregcm/tests/controllers/MessageControllerTest.java
index b892bcf9a..310469bc7 100644
--- a/service/src/test/java/org/whispersystems/textsecuregcm/tests/controllers/MessageControllerTest.java
+++ b/service/src/test/java/org/whispersystems/textsecuregcm/tests/controllers/MessageControllerTest.java
@@ -35,6 +35,7 @@ import org.whispersystems.textsecuregcm.push.ReceiptSender;
 import org.whispersystems.textsecuregcm.storage.Account;
 import org.whispersystems.textsecuregcm.storage.AccountsManager;
 import org.whispersystems.textsecuregcm.storage.Device;
+import org.whispersystems.textsecuregcm.storage.FeatureFlagsManager;
 import org.whispersystems.textsecuregcm.storage.MessagesManager;
 import org.whispersystems.textsecuregcm.tests.util.AuthHelper;
 import org.whispersystems.textsecuregcm.util.Base64;
@@ -86,6 +87,7 @@ public class MessageControllerTest {
   private  final RateLimiters           rateLimiters           = mock(RateLimiters.class);
   private  final RateLimiter            rateLimiter            = mock(RateLimiter.class);
   private  final ApnFallbackManager     apnFallbackManager     = mock(ApnFallbackManager.class);
+  private  final FeatureFlagsManager    featureFlagsManager    = mock(FeatureFlagsManager.class);
 
   private  final ObjectMapper mapper = new ObjectMapper();
 
@@ -95,7 +97,7 @@ public class MessageControllerTest {
                                                             .addProvider(new PolymorphicAuthValueFactoryProvider.Binder<>(ImmutableSet.of(Account.class, DisabledPermittedAccount.class)))
                                                             .setTestContainerFactory(new GrizzlyWebTestContainerFactory())
                                                             .addResource(new MessageController(rateLimiters, messageSender, receiptSender, accountsManager,
-                                                                                               messagesManager, apnFallbackManager))
+                                                                                               messagesManager, apnFallbackManager, featureFlagsManager))
                                                             .build();