diff --git a/apps/lifecycle/src/campaign/send.spec.ts b/apps/lifecycle/src/campaign/send.spec.ts
index 41d777163..377540a82 100644
--- a/apps/lifecycle/src/campaign/send.spec.ts
+++ b/apps/lifecycle/src/campaign/send.spec.ts
@@ -26,7 +26,7 @@ import {
   type LifecycleJobDependencies,
 } from './send.js';
 import { DeterministicLifecycleJobError } from '../job-errors.js';
-import { FOUNDER_BOOKING_URL } from './templates.js';
+import { BUSINESS_POSTAL_ADDRESS, FOUNDER_BOOKING_URL } from './templates.js';
 
 const NOW = new Date('2026-09-01T12:03:00.000Z');
 const CONTACT_ID = '00000000-0000-4000-8000-000000000002';
@@ -161,6 +161,13 @@ describe('prepareCampaignMessage', () => {
       if (prepared.status !== 'ready') throw new Error('expected ready');
       expect(prepared.text).toContain(unsubscribeActionUrlValue(UNSUBSCRIBE));
       expect(prepared.text).toContain('\n\n—\nBrian\n');
+      expect(
+        prepared.text.endsWith(
+          `${unsubscribeActionUrlValue(
+            UNSUBSCRIBE
+          )}\n${BUSINESS_POSTAL_ADDRESS}`
+        )
+      ).toBe(true);
       if (step === 3)
         expect(prepared.text).toContain('This is my last automated follow-up.');
     }
@@ -259,6 +266,13 @@ describe('prepareCampaignMessage', () => {
         '\n\n—\nBrian\n\nIs this email not relevant to you? Stop here: '
       );
       expect(prepared.text).toContain(unsubscribeActionUrlValue(UNSUBSCRIBE));
+      expect(
+        prepared.text.endsWith(
+          `${unsubscribeActionUrlValue(
+            UNSUBSCRIBE
+          )}\n${BUSINESS_POSTAL_ADDRESS}`
+        )
+      ).toBe(true);
       expect(prepared.text).not.toContain('ada@example.com');
     }
   );
@@ -300,7 +314,7 @@ describe('prepareCampaignMessage', () => {
     expect(prepared.html).toContain('<p>—<br>Brian</p>');
     expect(
       prepared.html.endsWith(
-        `<p>Is this email not relevant to you? Click <a href="${unsubscribeUrl}">here</a>.</p>`
+        `<p>Is this email not relevant to you? Click <a href="${unsubscribeUrl}">here</a>.</p>\n<p>${BUSINESS_POSTAL_ADDRESS}</p>`
       )
     ).toBe(true);
     expect(prepared.html.split(unsubscribeUrl)).toHaveLength(2);
@@ -309,7 +323,7 @@ describe('prepareCampaignMessage', () => {
     );
     expect(prepared.html).toContain(`href="${unsubscribeUrl}">here</a>`);
     expect(prepared.text).toContain(
-      `Is this email not relevant to you? Stop here: ${unsubscribeUrl}`
+      `Is this email not relevant to you? Stop here: ${unsubscribeUrl}\n${BUSINESS_POSTAL_ADDRESS}`
     );
   });
 
diff --git a/apps/lifecycle/src/campaign/send.ts b/apps/lifecycle/src/campaign/send.ts
index 6aa934f7d..85051546c 100644
--- a/apps/lifecycle/src/campaign/send.ts
+++ b/apps/lifecycle/src/campaign/send.ts
@@ -48,6 +48,7 @@ import { renderFulfillmentTemplate } from '../fulfillment/templates.js';
 import { renderInternalNotificationSummary } from '../notifications/templates.js';
 import { DeterministicLifecycleJobError } from '../job-errors.js';
 import {
+  BUSINESS_POSTAL_ADDRESS,
   renderCampaignTemplate,
   renderEvidenceCampaignTemplate,
   type CampaignDraft,
@@ -279,7 +280,7 @@ function signedText(
 ): string {
   return `${body}\n\n—\nBrian\n\nIs this email not relevant to you? Stop here: ${unsubscribeActionUrlValue(
     unsubscribeUrl
-  )}`;
+  )}\n${BUSINESS_POSTAL_ADDRESS}`;
 }
 
 const HTML_ESCAPES: Record<string, string> = {
@@ -315,8 +316,9 @@ function htmlLine(line: string): string {
 
 /**
  * A plain HTML alternative for the text part: the same paragraphs, bare HTTPS
- * links as anchors, and a one-word unsubscribe link instead of the long signed
- * URL. No layout, images, styles, or tracking.
+ * links as anchors, a one-word unsubscribe link instead of the long signed
+ * URL, and the business postal address as the final line. No layout, images,
+ * styles, or tracking.
  */
 function signedHtml(
   body: string,
@@ -331,6 +333,7 @@ function signedHtml(
     ...paragraphs,
     '<p>—<br>Brian</p>',
     `<p>Is this email not relevant to you? Click <a href="${unsubscribe}">here</a>.</p>`,
+    `<p>${escapeHtml(BUSINESS_POSTAL_ADDRESS)}</p>`,
   ].join('\n');
 }
 
diff --git a/apps/lifecycle/src/campaign/templates.ts b/apps/lifecycle/src/campaign/templates.ts
index 76c7d0aa4..bc3a8bf2a 100644
--- a/apps/lifecycle/src/campaign/templates.ts
+++ b/apps/lifecycle/src/campaign/templates.ts
@@ -21,6 +21,16 @@ const CampaignStepSchema = z.enum(['immediate', 'day-3', 'day-8']);
 export const FOUNDER_BOOKING_URL =
   'https://calendar.app.google/nK961tWHZd21izKR6';
 
+/**
+ * The business postal address every recipient-facing email prints after its
+ * unsubscribe line. CAN-SPAM requires a valid physical postal address on
+ * commercial mail, so the footer in `send.ts` renders this single constant in
+ * both the text and HTML parts. Keep it on one line; the HTML part escapes it
+ * into a bare `<p>`.
+ */
+export const BUSINESS_POSTAL_ADDRESS =
+  '2843 NW Lolo Dr, Bend, OR 97703, United States';
+
 /**
  * Every link recipient copy may carry, across campaign steps and fulfillment
  * mail. The four PDFs are the whitepaper fulfillment deliverables.
diff --git a/docs/superpowers/specs/2026-08-31-threadplane-growth-lifecycle-v1-design.md b/docs/superpowers/specs/2026-08-31-threadplane-growth-lifecycle-v1-design.md
index 0d1f70c28..d6f842420 100644
--- a/docs/superpowers/specs/2026-08-31-threadplane-growth-lifecycle-v1-design.md
+++ b/docs/superpowers/specs/2026-08-31-threadplane-growth-lifecycle-v1-design.md
@@ -674,6 +674,7 @@ apps/lifecycle should declare Dawn Core/CLI/LangGraph/Postgres Storage/SDK 0.8.2
 Copy constraints:
 
 - All recipient fulfillment, welcome, acknowledgment, and campaign mail is authored as plain text. Since 2026-09-05 the sender also attaches a plain HTML alternative rendered from that text (paragraphs and HTTPS anchors only) so the unsubscribe footer can read “click here” instead of the long signed URL; the sender rejects any HTML part containing images, scripts, styles, forms, event handlers, or a missing unsubscribe anchor.
+- Every recipient-facing email (campaign steps and fulfillment) ends with the business postal address on a single plain line directly after the unsubscribe line, in both the text and HTML parts, because CAN-SPAM requires a valid physical postal address on commercial mail. The address is sourced from the single exported constant `BUSINESS_POSTAL_ADDRESS` in the campaign templates; the HTML part renders it as one escaped `<p>` so the sender's paragraphs-and-links-only check still passes.
 - Internal research and operational notifications are plain text as well.
 - Each campaign step is at most 120 words.
 - At most one question and at most one useful link.