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 +1,91 @@
+// @flow
+
+import bots from 'lib/facts/bots';
+import { createMessageReply } from 'lib/shared/message-utils';
+import { type MessageReportCreationRequest } from 'lib/types/message-report-types';
+import { messageTypes } from 'lib/types/message-types';
+
+import { createCommbotThread } from '../bots/commbot';
+import { SQL } from '../database/database';
+import { fetchMessageInfoByID } from '../fetchers/message-fetchers';
+import {
+  fetchPersonalThreadID,
+  fetchServerThreadInfos,
+} from '../fetchers/thread-fetchers';
+import { fetchUsername } from '../fetchers/user-fetchers';
+import { createBotViewer } from '../session/bots';
+import type { Viewer } from '../session/viewer';
+import createMessages from './message-creator';
+
+const { commbot } = bots;
+
+async function getCommbotThreadID(userID: string): Promise<string> {
+  let commbotThreadID = await fetchPersonalThreadID(userID, commbot.userID);
+  if (!commbotThreadID) {
+    commbotThreadID = createCommbotThread(userID);
+  }
+  return commbotThreadID;
+}
+
+async function createMessageReport(
+  viewer: Viewer,
+  request: MessageReportCreationRequest,
+  recipientID: string,
+) {
+  const threadUserInfoPromise = Promise.all([
+    fetchUsername(viewer.id),
+    getCommbotThreadID(recipientID),
+  ]);
+
+  const reportedMessage = await fetchMessageInfoByID(viewer, request.messageID);
+
+  const reportedThreadID = reportedMessage?.threadID ?? '[null]';
+  const reportedMessageAuthorID = reportedMessage?.creatorID;
+
+  const reportedPromise = Promise.all([
+    fetchServerThreadInfos(SQL`t.id = ${reportedThreadID}`),
+    fetchUsername(reportedMessageAuthorID ?? '[null]'),
+  ]);
+
+  const reportedMessageText =
+    reportedMessage?.type === 0 ? reportedMessage.text : '[null]';
+
+  const [viewerUsername, commbotThreadID] = await threadUserInfoPromise;
+  const [reportedThread, reportedMessageAuthor] = await reportedPromise;
+
+  const reportMessage = getCommbotMessage(
+    viewerUsername,
+    reportedMessageAuthor,
+    reportedThread.threadInfos[reportedThreadID]?.name,
+    reportedMessageText,
+  );
+  const time = Date.now();
+  await createMessages(createBotViewer(commbot.userID), [
+    {
+      type: messageTypes.TEXT,
+      threadID: commbotThreadID,
+      creatorID: commbot.userID,
+      time,
+      text: reportMessage,
+    },
+  ]);
+}
+
+function getCommbotMessage(
+  reporterUsername: ?string,
+  messageAuthorUsername: ?string,
+  threadName: ?string,
+  message: string,
+): string {
+  reporterUsername = reporterUsername ?? '[null]';
+  const messageAuthor = messageAuthorUsername
+    ? `${messageAuthorUsername}’s`
+    : 'this';
+  const thread = threadName ? `chat titled "${threadName}"` : 'chat';
+  return (
+    `user ${reporterUsername} reported ${messageAuthor} message in ${thread}\n` +
+    createMessageReply(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 +1,5 @@
+// @flow
+
+export type MessageReportCreationRequest = {
+  +messageID: string,
+};