diff --git a/keyserver/src/responders/message-responders.js b/keyserver/src/responders/message-responders.js
--- a/keyserver/src/responders/message-responders.js
+++ b/keyserver/src/responders/message-responders.js
@@ -104,8 +104,15 @@
     sendMultimediaMessageRequestInputValidator,
     request,
   );
+  return legacyMultimediaMessageCreationResponder(viewer, request);
+}
 
+async function legacyMultimediaMessageCreationResponder(
+  viewer: Viewer,
+  request: SendMultimediaMessageRequest,
+): Promise<SendMessageResponse> {
   const { threadID, localID, mediaIDs } = request;
+
   if (mediaIDs.length === 0) {
     throw new ServerError('invalid_parameters');
   }