diff --git a/keyserver/src/endpoints.js b/keyserver/src/endpoints.js
--- a/keyserver/src/endpoints.js
+++ b/keyserver/src/endpoints.js
@@ -18,6 +18,7 @@
 } from './responders/entry-responders';
 import type { JSONResponder } from './responders/handlers';
 import { getSessionPublicKeysResponder } from './responders/keys-responders';
+import { messageReportCreationResponder } from './responders/message-report-responder';
 import {
   textMessageCreationResponder,
   messageFetchResponder,
@@ -58,6 +59,7 @@
   create_account: accountCreationResponder,
   create_entry: entryCreationResponder,
   create_error_report: reportCreationResponder,
+  create_message_report: messageReportCreationResponder,
   create_multimedia_message: multimediaMessageCreationResponder,
   create_report: reportCreationResponder,
   create_reports: reportMultiCreationResponder,
diff --git a/keyserver/src/responders/message-report-responder.js b/keyserver/src/responders/message-report-responder.js
new file mode 100644
--- /dev/null
+++ b/keyserver/src/responders/message-report-responder.js
@@ -0,0 +1,48 @@
+// @flow
+
+import t from 'tcomb';
+
+import { getKeyserverAdmin } from 'lib/shared/user-utils';
+import { type MessageReportCreationRequest } from 'lib/types/message-report-types';
+import { tShape } from 'lib/utils/validation-utils';
+
+import createMessageReport from '../creators/message-report-creator';
+import { fetchMessageInfoByID } from '../fetchers/message-fetchers';
+import { serverThreadInfoFromMessageInfo } from '../fetchers/thread-fetchers';
+import { fetchAllUserIDs, fetchUserInfos } from '../fetchers/user-fetchers';
+import type { Viewer } from '../session/viewer';
+import { validateInput } from '../utils/validation-utils';
+
+const messageReportCreationRequestInputValidator = tShape({
+  messageID: t.String,
+});
+
+async function messageReportCreationResponder(viewer: Viewer, input: any) {
+  await validateInput(
+    viewer,
+    messageReportCreationRequestInputValidator,
+    input,
+  );
+  const request: MessageReportCreationRequest = input;
+
+  const userInfos = await fetchUserInfos(await fetchAllUserIDs());
+  const reportedMessage = await fetchMessageInfoByID(viewer, request.messageID);
+  const threadInfo = await serverThreadInfoFromMessageInfo(reportedMessage);
+
+  if (!threadInfo) {
+    return;
+  }
+  const keyserverAdmin = getKeyserverAdmin(threadInfo, userInfos);
+  if (!keyserverAdmin?.id) {
+    return;
+  }
+
+  await createMessageReport(
+    viewer,
+    reportedMessage,
+    threadInfo,
+    keyserverAdmin.id,
+  );
+}
+
+export { messageReportCreationResponder };
diff --git a/lib/types/endpoints.js b/lib/types/endpoints.js
--- a/lib/types/endpoints.js
+++ b/lib/types/endpoints.js
@@ -48,6 +48,7 @@
 const socketPreferredEndpoints = Object.freeze({
   CREATE_ENTRY: 'create_entry',
   CREATE_ERROR_REPORT: 'create_error_report',
+  CREATE_MESSAGE_REPORT: 'create_message_report',
   CREATE_MULTIMEDIA_MESSAGE: 'create_multimedia_message',
   CREATE_TEXT_MESSAGE: 'create_text_message',
   CREATE_THREAD: 'create_thread',