diff --git a/apps/api/src/automation/process-ongoing-sequence.test.ts b/apps/api/src/automation/process-ongoing-sequence.test.ts
index d17d1a2..6058320 100644
--- a/apps/api/src/automation/process-ongoing-sequence.test.ts
+++ b/apps/api/src/automation/process-ongoing-sequence.test.ts
@@ -13,6 +13,7 @@ vi.mock("../mail/send", () => ({
 
 import { db } from "../db/client";
 import { sendMail } from "../mail/send";
+import { getUnsubLink } from "../utils/mail";
 import {
     contacts,
     emailDeliveries,
@@ -125,6 +126,10 @@ describe("processOngoingSequence", () => {
         expect(sent.to).toBe(contact.email);
         expect(sent.subject).toBe("First");
         expect(sent.from).toBe("Test Sender <sender@example.com>");
+        expect(sent.headers).toEqual({
+            "List-Unsubscribe": `<${getUnsubLink(contact.unsubscribeToken)}>`,
+            "List-Unsubscribe-Post": "List-Unsubscribe=One-Click",
+        });
 
         const deliveries = await tdb
             .select()
diff --git a/apps/api/src/automation/process-ongoing-sequence.ts b/apps/api/src/automation/process-ongoing-sequence.ts
index 092414e..dab36ed 100644
--- a/apps/api/src/automation/process-ongoing-sequence.ts
+++ b/apps/api/src/automation/process-ongoing-sequence.ts
@@ -25,6 +25,7 @@ import {
     getTrackedClickUrl,
     getTrackingPixelUrl,
     getUnsubLink,
+    getListUnsubscribeHeaders,
 } from "../utils/mail";
 import { generatePixelToken } from "../utils/pixel-jwt";
 import logger from "../services/log";
@@ -327,6 +328,7 @@ async function attemptMailSending({
             espConfigId: pin.espConfigId,
             secretVersion: pin.secretVersion,
             messageId: rfcMessageId,
+            headers: getListUnsubscribeHeaders(contact.unsubscribeToken),
         });
         const [delivery] = await db
             .insert(emailDeliveries)
diff --git a/apps/api/src/tracking/routes.test.ts b/apps/api/src/tracking/routes.test.ts
index aa95143..a7c3723 100644
--- a/apps/api/src/tracking/routes.test.ts
+++ b/apps/api/src/tracking/routes.test.ts
@@ -55,13 +55,27 @@ type TestResponse = {
 };
 
 async function get(path: string): Promise<TestResponse> {
+    return request("GET", path);
+}
+
+async function request(
+    method: string,
+    path: string,
+    body?: string,
+    contentType?: string,
+): Promise<TestResponse> {
     const app = express();
     app.use(trackingRoutes);
 
     const req = new IncomingMessage(new Socket());
-    req.method = "GET";
+    req.method = method;
     req.url = path;
     req.headers = { host: "localhost:5000" };
+    if (body !== undefined) {
+        req.headers["content-type"] =
+            contentType ?? "application/x-www-form-urlencoded";
+        req.headers["content-length"] = String(Buffer.byteLength(body));
+    }
 
     const res = new ServerResponse(req);
     const chunks: Buffer[] = [];
@@ -84,6 +98,7 @@ async function get(path: string): Promise<TestResponse> {
     });
 
     (app as any).handle(req, res);
+    if (body !== undefined) req.push(body);
     req.push(null);
     return done;
 }
@@ -229,4 +244,27 @@ describe("tracking and unsubscribe routes", () => {
         const unknown = await get("/unsubscribe/unknown");
         expect(unknown.status).toBe(404);
     });
+
+    it("unsubscribes on an RFC 8058 one-click POST without a confirmation page", async () => {
+        mocks.getContactByUnsubscribeToken.mockResolvedValue({
+            teamId: "team-internal",
+            contactId: "cnt_public",
+            email: "reader@example.com",
+            subscribed: true,
+        });
+
+        const response = await request(
+            "POST",
+            "/unsubscribe/unsub-token",
+            "List-Unsubscribe=One-Click",
+        );
+
+        expect(response.status).toBe(200);
+        expect(response.body.toString()).not.toContain("<form");
+        expect(mocks.updateContact).toHaveBeenCalledWith(
+            "team-internal",
+            "cnt_public",
+            { subscribed: false },
+        );
+    });
 });
diff --git a/apps/api/src/utils/mail.ts b/apps/api/src/utils/mail.ts
index 0165a8b..43c447e 100644
--- a/apps/api/src/utils/mail.ts
+++ b/apps/api/src/utils/mail.ts
@@ -10,6 +10,22 @@ export function getUnsubLink(unsubscribeToken: string): string {
     return `${getSiteUrl()}/unsubscribe/${unsubscribeToken}`;
 }
 
+/**
+ * RFC 2369 / RFC 8058 headers for marketing (broadcast and sequence) mail.
+ * Mailbox providers POST `List-Unsubscribe=One-Click` to the https URL, which
+ * `tracking/routes.ts` handles without a confirmation page. The URL is the
+ * contact's existing per-contact unsubscribe link. No mailto is included
+ * because there is no configured unsubscribe mailbox to receive it.
+ */
+export function getListUnsubscribeHeaders(
+    unsubscribeToken: string,
+): Record<string, string> {
+    return {
+        "List-Unsubscribe": `<${getUnsubLink(unsubscribeToken)}>`,
+        "List-Unsubscribe-Post": "List-Unsubscribe=One-Click",
+    };
+}
+
 export function getTrackingPixelUrl(token: string): string {
     return `${getSiteUrl()}/track/open?d=${token}`;
 }