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 06da37ea3..56120af90 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 @@ import io.micrometer.core.instrument.Metrics;
 import io.micrometer.core.instrument.Tag;
 import io.micrometer.core.instrument.Tags;
 import java.security.MessageDigest;
+import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Base64;
@@ -98,6 +99,7 @@ import org.whispersystems.textsecuregcm.util.ua.UnrecognizedUserAgentException;
 import org.whispersystems.textsecuregcm.util.ua.UserAgentUtil;
 import org.whispersystems.textsecuregcm.websocket.WebSocketConnection;
 import org.whispersystems.websocket.Stories;
+import reactor.core.scheduler.Schedulers;
 
 @SuppressWarnings("OptionalUsedAsFieldOrParameterType")
 @Path("/v1/messages")
@@ -482,7 +484,7 @@ public class MessageController {
   @Timed
   @GET
   @Produces(MediaType.APPLICATION_JSON)
-  public OutgoingMessageEntityList getPendingMessages(@Auth AuthenticatedAccount auth,
+  public CompletableFuture<OutgoingMessageEntityList> getPendingMessages(@Auth AuthenticatedAccount auth,
       @HeaderParam(Stories.X_SIGNAL_RECEIVE_STORIES) String receiveStoriesHeader,
       @HeaderParam("User-Agent") String userAgent) {
 
@@ -490,39 +492,40 @@ public class MessageController {
 
     pushNotificationManager.handleMessagesRetrieved(auth.getAccount(), auth.getAuthenticatedDevice(), userAgent);
 
-    final OutgoingMessageEntityList outgoingMessages;
-    {
-      final Pair<List<Envelope>, Boolean> messagesAndHasMore = messagesManager.getMessagesForDevice(
-          auth.getAccount().getUuid(),
-          auth.getAuthenticatedDevice().getId(),
-          false);
+    return messagesManager.getMessagesForDevice(
+            auth.getAccount().getUuid(),
+            auth.getAuthenticatedDevice().getId(),
+            false)
+        .map(messagesAndHasMore -> {
+          Stream<Envelope> envelopes = messagesAndHasMore.first().stream();
+          if (!shouldReceiveStories) {
+            envelopes = envelopes.filter(e -> !e.getStory());
+          }
 
-      Stream<Envelope> envelopes = messagesAndHasMore.first().stream();
-      if (!shouldReceiveStories) {
-        envelopes = envelopes.filter(e -> !e.getStory());
-      }
+          final OutgoingMessageEntityList messages = new OutgoingMessageEntityList(envelopes
+              .map(OutgoingMessageEntity::fromEnvelope)
+              .peek(
+                  outgoingMessageEntity -> MessageMetrics.measureAccountOutgoingMessageUuidMismatches(auth.getAccount(),
+                      outgoingMessageEntity))
+              .collect(Collectors.toList()),
+              messagesAndHasMore.second());
 
-      outgoingMessages = new OutgoingMessageEntityList(envelopes
-          .map(OutgoingMessageEntity::fromEnvelope)
-          .peek(outgoingMessageEntity -> MessageMetrics.measureAccountOutgoingMessageUuidMismatches(auth.getAccount(),
-              outgoingMessageEntity))
-          .collect(Collectors.toList()),
-          messagesAndHasMore.second());
-    }
+          String platform;
 
-    {
-      String platform;
+          try {
+            platform = UserAgentUtil.parseUserAgentString(userAgent).getPlatform().name().toLowerCase();
+          } catch (final UnrecognizedUserAgentException ignored) {
+            platform = "unrecognized";
+          }
 
-      try {
-        platform = UserAgentUtil.parseUserAgentString(userAgent).getPlatform().name().toLowerCase();
-      } catch (final UnrecognizedUserAgentException ignored) {
-        platform = "unrecognized";
-      }
+          Metrics.summary(OUTGOING_MESSAGE_LIST_SIZE_BYTES_DISTRIBUTION_NAME, "platform", platform)
+              .record(estimateMessageListSizeBytes(messages));
 
-      Metrics.summary(OUTGOING_MESSAGE_LIST_SIZE_BYTES_DISTRIBUTION_NAME, "platform", platform).record(estimateMessageListSizeBytes(outgoingMessages));
-    }
-
-    return outgoingMessages;
+          return messages;
+        })
+        .timeout(Duration.ofSeconds(5))
+        .subscribeOn(Schedulers.boundedElastic())
+        .toFuture();
   }
 
   private static long estimateMessageListSizeBytes(final OutgoingMessageEntityList messageList) {
diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/storage/MessagesManager.java b/service/src/main/java/org/whispersystems/textsecuregcm/storage/MessagesManager.java
index d11589e0e..de50f8680 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/storage/MessagesManager.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/storage/MessagesManager.java
@@ -27,7 +27,7 @@ import org.whispersystems.textsecuregcm.metrics.MetricsUtil;
 import org.whispersystems.textsecuregcm.util.Constants;
 import org.whispersystems.textsecuregcm.util.Pair;
 import reactor.core.publisher.Flux;
-import reactor.core.scheduler.Schedulers;
+import reactor.core.publisher.Mono;
 
 public class MessagesManager {
 
@@ -72,23 +72,14 @@ public class MessagesManager {
     return messagesCache.hasMessages(destinationUuid, destinationDevice);
   }
 
-  public Pair<List<Envelope>, Boolean> getMessagesForDevice(UUID destinationUuid, long destinationDevice,
+  public Mono<Pair<List<Envelope>, Boolean>> getMessagesForDevice(UUID destinationUuid, long destinationDevice,
       boolean cachedMessagesOnly) {
 
-    try {
-      final List<Envelope> envelopes = Flux.from(
-              getMessagesForDevice(destinationUuid, destinationDevice, RESULT_SET_CHUNK_SIZE, cachedMessagesOnly))
-          .take(RESULT_SET_CHUNK_SIZE, true)
-          .collectList()
-          .subscribeOn(Schedulers.boundedElastic())
-          .toFuture()
-          .get(5, TimeUnit.SECONDS);
-
-      return new Pair<>(envelopes, envelopes.size() >= RESULT_SET_CHUNK_SIZE);
-    } catch (Exception e) {
-      throw new RuntimeException(e);
-    }
-
+    return Flux.from(
+            getMessagesForDevice(destinationUuid, destinationDevice, RESULT_SET_CHUNK_SIZE, cachedMessagesOnly))
+        .take(RESULT_SET_CHUNK_SIZE, true)
+        .collectList()
+        .map(envelopes -> new Pair<>(envelopes, envelopes.size() >= RESULT_SET_CHUNK_SIZE));
   }
 
   public Publisher<Envelope> getMessagesForDeviceReactive(UUID destinationUuid, long destinationDevice,
diff --git a/service/src/test/java/org/whispersystems/textsecuregcm/controllers/MessageControllerTest.java b/service/src/test/java/org/whispersystems/textsecuregcm/controllers/MessageControllerTest.java
index 3a2caa3e1..42ac33d79 100644
--- a/service/src/test/java/org/whispersystems/textsecuregcm/controllers/MessageControllerTest.java
+++ b/service/src/test/java/org/whispersystems/textsecuregcm/controllers/MessageControllerTest.java
@@ -54,6 +54,7 @@ import javax.ws.rs.client.Entity;
 import javax.ws.rs.client.Invocation;
 import javax.ws.rs.core.MediaType;
 import javax.ws.rs.core.Response;
+import org.glassfish.jersey.server.ServerProperties;
 import org.glassfish.jersey.test.grizzly.GrizzlyWebTestContainerFactory;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
@@ -96,6 +97,7 @@ import org.whispersystems.textsecuregcm.tests.util.AuthHelper;
 import org.whispersystems.textsecuregcm.util.Pair;
 import org.whispersystems.textsecuregcm.util.SystemMapper;
 import org.whispersystems.websocket.Stories;
+import reactor.core.publisher.Mono;
 
 @ExtendWith(DropwizardExtensionsSupport.class)
 class MessageControllerTest {
@@ -138,6 +140,7 @@ class MessageControllerTest {
   private static final ExecutorService multiRecipientMessageExecutor = mock(ExecutorService.class);
 
   private static final ResourceExtension resources = ResourceExtension.builder()
+      .addProperty(ServerProperties.UNWRAP_COMPLETION_STAGE_IN_WRITER_ENABLE, Boolean.TRUE)
       .addProvider(AuthHelper.getAuthFilter())
       .addProvider(new PolymorphicAuthValueFactoryProvider.Binder<>(
           ImmutableSet.of(AuthenticatedAccount.class, DisabledPermittedAuthenticatedAccount.class)))
@@ -461,7 +464,7 @@ class MessageControllerTest {
     );
 
     when(messagesManager.getMessagesForDevice(eq(AuthHelper.VALID_UUID), eq(1L), anyBoolean()))
-        .thenReturn(new Pair<>(envelopes, false));
+        .thenReturn(Mono.just(new Pair<>(envelopes, false)));
 
     final String userAgent = "Test-UA";
 
@@ -515,7 +518,7 @@ class MessageControllerTest {
     );
 
     when(messagesManager.getMessagesForDevice(eq(AuthHelper.VALID_UUID), eq(1L), anyBoolean()))
-        .thenReturn(new Pair<>(messages, false));
+        .thenReturn(Mono.just(new Pair<>(messages, false)));
 
     Response response =
         resources.getJerseyTest().target("/v1/messages/")
@@ -528,7 +531,7 @@ class MessageControllerTest {
   }
 
   @Test
-  void testDeleteMessages() throws Exception {
+  void testDeleteMessages() {
     long timestamp = System.currentTimeMillis();
 
     UUID sourceUuid = UUID.randomUUID();