diff --git a/index.ts b/index.ts
index 3cc0623..1292d83 100644
--- a/index.ts
+++ b/index.ts
@@ -18,6 +18,10 @@ export const ISSUE_REPORT =
   process.env.ISSUE_REPORT ?? "mailto:kill-the-newsletter@leafac.com";
 
 export const webServer = express()
+  .use(["/feeds", "/alternate"], (req, res, next) => {
+    res.header("X-Robots-Tag", "noindex");
+    next();
+  })
   .use(express.static("static"))
   .use(express.urlencoded({ extended: true }))
   .get("/", (req, res) => res.send(layout(newInbox())))
diff --git a/test.ts b/test.ts
index 0e11e32..8c063e1 100644
--- a/test.ts
+++ b/test.ts
@@ -221,6 +221,20 @@ describe("receive email", () => {
   });
 });
 
+test("‘noindex’ header", async () => {
+  const identifier = await createFeed();
+  const feed = await getFeed(identifier);
+  const entry = feed.querySelector("feed > entry:first-of-type")!;
+  const alternatePath = entry.querySelector("link")!.getAttribute("href")!;
+  expect((await webClient.get(`/`)).headers["x-robots-tag"]).toBeUndefined();
+  expect(
+    (await webClient.get(`/feeds/${identifier}.xml`)).headers["x-robots-tag"]
+  ).toBe("noindex");
+  expect((await webClient.get(alternatePath)).headers["x-robots-tag"]).toBe(
+    "noindex"
+  );
+});
+
 const webClient = axios.create({
   baseURL: BASE_URL,
 });