diff --git a/backend/src/routes/cartCheckout.ts b/backend/src/routes/cartCheckout.ts
index b585a29..ec708ed 100644
--- a/backend/src/routes/cartCheckout.ts
+++ b/backend/src/routes/cartCheckout.ts
@@ -246,9 +246,20 @@ router.post('/demo/purchase', requireCustomer, asyncRoute(async (req: Request, r
     const opened = await openCheckout(client, req.customerId as number, shippingAddressId, 'demo', `demo-${Date.now()}`);
     if (!opened.ok) { await client.query('ROLLBACK'); return res.status(400).json({ error: opened.error }); }
 
-    const sold = await completeCheckout(client, opened.checkoutId, 'demo', null, { demo: true });
+    await completeCheckout(client, opened.checkoutId, 'demo', null, { demo: true });
     await client.query('COMMIT');
-    await notifyFavoritersOfSale(sold.itemIds, sold.buyerId);
+
+    // Deliberately no notifyFavoritersOfSale here, unlike the PayPal capture and
+    // webhook paths above. A demo purchase is not a sale. The item really is
+    // marked sold, so the storefront stays truthful about availability, but the
+    // `favoriteSold` copy says the item "has been sold to another customer" and
+    // "will not be restocked" — and both are false when nobody bought anything.
+    //
+    // This is the only outbound consequence a demo purchase has. Everything else
+    // it does is visible to the person who clicked, who has been told it is a
+    // demo (#195, #203); these recipients never saw the cart and have no way to
+    // know. While production runs the demo interim (#191) they are real
+    // customers on real SMTP. See #206.
     res.json({ status: 'completed' });
   } catch (err) {
     await client.query('ROLLBACK');
diff --git a/backend/tests/integration/favorites.integration.test.ts b/backend/tests/integration/favorites.integration.test.ts
index 24e3b56..58aa054 100644
--- a/backend/tests/integration/favorites.integration.test.ts
+++ b/backend/tests/integration/favorites.integration.test.ts
@@ -7,6 +7,7 @@ jest.mock('../../src/mailer', () => ({
   sendMail: jest.fn().mockResolvedValue(undefined)
 }));
 import { sendMail } from '../../src/mailer';
+import { notifyFavoritersOfSale } from '../../src/favoriteAlerts';
 const sentMail = sendMail as jest.MockedFunction<typeof sendMail>;
 
 beforeEach(async () => {
@@ -168,36 +169,69 @@ describe('notifying when a favorited item sells', () => {
     expect(purchase.status).toBeLessThan(400);
   }
 
+  // The demo route deliberately notifies nobody (#206) and the PayPal path has
+  // no integration coverage, so the tests below call the notifier the way the
+  // PayPal capture and webhook routes do — after the purchase, with the sold
+  // ids and the buyer. That keeps them about *who* gets told, which is what
+  // they were testing all along; whether the demo route itself notifies is
+  // asserted separately, above.
+  async function buyThenNotify(
+    agent: ReturnType<typeof request.agent>,
+    itemId: number,
+    buyerId: number | null
+  ) {
+    await buyViaDemo(agent, itemId);
+    await notifyFavoritersOfSale([itemId], buyerId);
+  }
+
   it('emails a favoriter who opted in', async () => {
     const itemId = await createItem('Wanted item');
     const { agent: watcher } = await register('watcher@example.com');
     await watcher.post(`/api/customers/me/favorites/${itemId}`);
     await watcher.put('/api/customers/me/favorite-alerts').send({ enabled: true });
 
-    const { agent: buyer } = await register('buyer@example.com');
-    await buyViaDemo(buyer, itemId);
+    const { agent: buyer, id: buyerId } = await register('buyer@example.com');
+    await buyThenNotify(buyer, itemId, buyerId);
 
     expect(soldNotificationsTo()).toEqual(['watcher@example.com']);
   });
 
+  // A demo purchase is not a sale. The item really is marked sold, so the
+  // storefront is telling the truth about availability, but nobody bought
+  // anything and nobody is shipping anything — and while production runs the
+  // demo interim (#191) this mail reaches real favoriters through real SMTP,
+  // telling them an item "has been sold to another customer" and "will not be
+  // restocked". Both are false. See #206.
+  it('sends nothing when the purchase was a demo', async () => {
+    const itemId = await createItem('Demo bought');
+    const { agent: watcher } = await register('watcher-demo@example.com');
+    await watcher.post(`/api/customers/me/favorites/${itemId}`);
+    await watcher.put('/api/customers/me/favorite-alerts').send({ enabled: true });
+
+    const { agent: buyer } = await register('demo-buyer@example.com');
+    await buyViaDemo(buyer, itemId);
+
+    expect(soldNotificationsTo()).toEqual([]);
+  });
+
   it('does not email a favoriter who never opted in', async () => {
     const itemId = await createItem('Wanted item');
     const { agent: watcher } = await register('silent@example.com');
     await watcher.post(`/api/customers/me/favorites/${itemId}`);
 
-    const { agent: buyer } = await register('buyer2@example.com');
-    await buyViaDemo(buyer, itemId);
+    const { agent: buyer, id: buyerId } = await register('buyer2@example.com');
+    await buyThenNotify(buyer, itemId, buyerId);
 
     expect(soldNotificationsTo()).toEqual([]);
   });
 
   it('does not tell the buyer their own purchase is unavailable', async () => {
     const itemId = await createItem('Self bought');
-    const { agent: buyer } = await register('selfbuy@example.com');
+    const { agent: buyer, id: buyerId } = await register('selfbuy@example.com');
     await buyer.post(`/api/customers/me/favorites/${itemId}`);
     await buyer.put('/api/customers/me/favorite-alerts').send({ enabled: true });
 
-    await buyViaDemo(buyer, itemId);
+    await buyThenNotify(buyer, itemId, buyerId);
 
     expect(soldNotificationsTo()).toEqual([]);
   });
@@ -210,10 +244,10 @@ describe('notifying when a favorited item sells', () => {
       await agent.put('/api/customers/me/favorite-alerts').send({ enabled: true });
     }
 
-    const { agent: buyer } = await register('c@example.com');
+    const { agent: buyer, id: buyerId } = await register('c@example.com');
     await buyer.post(`/api/customers/me/favorites/${itemId}`);
     await buyer.put('/api/customers/me/favorite-alerts').send({ enabled: true });
-    await buyViaDemo(buyer, itemId);
+    await buyThenNotify(buyer, itemId, buyerId);
 
     expect(soldNotificationsTo().sort()).toEqual(['a@example.com', 'b@example.com']);
   });