diff --git a/keyserver/src/creators/message-report-creator.js b/keyserver/src/creators/message-report-creator.js
new file mode 100644
--- /dev/null
+++ b/keyserver/src/creators/message-report-creator.js
@@ -0,0 +1,60 @@
+// @flow
+
+import bots from 'lib/facts/bots';
+import { type MessageReportCreationRequest } from 'lib/types/message-report-types';
+import { messageTypes } from 'lib/types/message-types';
+
+import { fetchUsername } from '../fetchers/user-fetchers';
+import { handleAsyncPromise } from '../responders/handlers';
+import { createBotViewer } from '../session/bots';
+import type { Viewer } from '../session/viewer';
+import createMessages from './message-creator';
+
+const { commbot } = bots;
+
+async function createMessageReport(
+  viewer: Viewer,
+  request: MessageReportCreationRequest,
+) {
+  handleAsyncPromise(sendCommbotMessage(viewer, request));
+}
+
+async function sendCommbotMessage(
+  viewer: Viewer,
+  request: MessageReportCreationRequest,
+) {
+  const username = await fetchUsername(viewer.id);
+  if (!username) {
+    return;
+  }
+  const message = getCommbotMessage(request, username);
+
+  const time = Date.now();
+  await createMessages(createBotViewer(commbot.userID), [
+    {
+      type: messageTypes.TEXT,
+      threadID: commbot.staffThreadID,
+      creatorID: commbot.userID,
+      time,
+      text: message,
+    },
+  ]);
+}
+
+function getCommbotMessage(
+  request: MessageReportCreationRequest,
+  username: string,
+): string {
+  const messageAuthor = request.messageAuthorInfo.username
+    ? `${request.messageAuthorInfo.username}’s`
+    : 'this';
+  const thread = request.thread?.name
+    ? `chat titled "${request.thread.name}"`
+    : 'chat';
+  return (
+    `user ${username} reported ${messageAuthor} message in ${thread}\n` +
+    `> ${request.message}`
+  );
+}
+
+export default createMessageReport;
diff --git a/lib/types/message-report-types.js b/lib/types/message-report-types.js
new file mode 100644
--- /dev/null
+++ b/lib/types/message-report-types.js
@@ -0,0 +1,10 @@
+// @flow
+
+import { type ThreadInfo } from './thread-types';
+import type { UserInfo } from './user-types';
+
+export type MessageReportCreationRequest = {
+  +thread: ThreadInfo,
+  +messageAuthorInfo: UserInfo,
+  +message: string,
+};