diff --git a/e2e/fixtures/test-helpers.ts b/e2e/fixtures/test-helpers.ts
index bbc44b95..b30e3d53 100644
--- a/e2e/fixtures/test-helpers.ts
+++ b/e2e/fixtures/test-helpers.ts
@@ -29,7 +29,8 @@ export async function createTestAddress(
 }
 
 /**
- * Seed a test email into the worker DB via the admin test endpoint.
+ * Seed a test email by exercising the real worker email() handler
+ * via the admin test endpoint.
  */
 export async function seedTestMail(
   ctx: APIRequestContext,
@@ -41,11 +42,13 @@ export async function seedTestMail(
   const boundary = `----E2E${Date.now()}`;
   const htmlPart = opts.html || `<p>${opts.text || 'Hello from E2E'}</p>`;
   const textPart = opts.text || 'Hello from E2E';
+  const messageId = `<e2e-${Date.now()}-${Math.random().toString(36).slice(2, 10)}@test>`;
 
   const raw = [
     `From: ${from}`,
     `To: ${address}`,
     `Subject: ${subject}`,
+    `Message-ID: ${messageId}`,
     `MIME-Version: 1.0`,
     `Content-Type: multipart/alternative; boundary="${boundary}"`,
     ``,
@@ -60,12 +63,16 @@ export async function seedTestMail(
     `--${boundary}--`,
   ].join('\r\n');
 
-  const res = await ctx.post(`${WORKER_URL}/admin/test/seed_mail`, {
-    data: { address, source: from, raw },
+  const res = await ctx.post(`${WORKER_URL}/admin/test/receive_mail`, {
+    data: { from, to: address, raw },
   });
   if (!res.ok()) {
     throw new Error(`Failed to seed mail: ${res.status()} ${await res.text()}`);
   }
+  const body = await res.json();
+  if (!body.success) {
+    throw new Error(`Mail was rejected: ${body.rejected || 'unknown reason'}`);
+  }
 }
 
 /**
diff --git a/worker/src/admin_api/e2e_test_api.ts b/worker/src/admin_api/e2e_test_api.ts
new file mode 100644
index 00000000..f5af30f7
--- /dev/null
+++ b/worker/src/admin_api/e2e_test_api.ts
@@ -0,0 +1,63 @@
+import { Context } from 'hono'
+import { getBooleanValue } from '../utils'
+
+// Direct DB insert — bypasses the email() handler.
+const seedMail = async (c: Context<HonoCustomType>) => {
+    if (!getBooleanValue(c.env.E2E_TEST_MODE)) {
+        return c.text("Not available", 404);
+    }
+    const { address, source, raw, message_id } = await c.req.json();
+    if (!address || !raw) {
+        return c.text("address and raw are required", 400);
+    }
+    if (raw.length > 1_000_000) {
+        return c.text("raw content too large", 400);
+    }
+    if (message_id && message_id.length > 255) {
+        return c.text("message_id too long", 400);
+    }
+    const msgId = message_id || `<e2e-${Date.now()}@test>`;
+    const { success } = await c.env.DB.prepare(
+        `INSERT INTO raw_mails (message_id, source, address, raw, created_at)`
+        + ` VALUES (?, ?, ?, ?, datetime('now'))`
+    ).bind(msgId, source || address, address, raw).run();
+    return c.json({ success });
+};
+
+// Exercises the real email() handler with a mock ForwardableEmailMessage.
+const receiveMail = async (c: Context<HonoCustomType>) => {
+    if (!getBooleanValue(c.env.E2E_TEST_MODE)) {
+        return c.text("Not available", 404);
+    }
+    const { from, to, raw } = await c.req.json();
+    if (!from || !to || !raw) {
+        return c.text("from, to and raw are required", 400);
+    }
+
+    // Parse MIME headers (unfold continuation lines, extract key:value pairs)
+    const headerSection = raw.substring(0, Math.max(0, raw.indexOf('\r\n\r\n')));
+    const headers = new Headers();
+    for (const line of headerSection.replace(/\r\n(?=[ \t])/g, ' ').split('\r\n')) {
+        const idx = line.indexOf(':');
+        if (idx > 0) headers.append(line.substring(0, idx).trim(), line.substring(idx + 1).trim());
+    }
+    if (!headers.has('Message-ID')) headers.set('Message-ID', `<e2e-${Date.now()}@test>`);
+
+    const rawBytes = new TextEncoder().encode(raw);
+    let rejected: string | undefined;
+    const mockMessage: ForwardableEmailMessage = {
+        from, to, headers,
+        rawSize: rawBytes.byteLength,
+        raw: new ReadableStream({ start(ctrl) { ctrl.enqueue(rawBytes); ctrl.close(); } }),
+        setReject(reason: string) { rejected = reason; },
+        forward: async () => ({ messageId: '' }),
+        reply: async () => ({ messageId: '' }),
+    };
+
+    const { email: emailHandler } = await import('../email');
+    await emailHandler(mockMessage, c.env, { waitUntil: () => {}, passThroughOnException: () => {} });
+
+    return c.json({ success: !rejected, ...(rejected ? { rejected } : {}) });
+};
+
+export default { seedMail, receiveMail };
diff --git a/worker/src/admin_api/index.ts b/worker/src/admin_api/index.ts
index 8ee6e519..c3fd143f 100644
--- a/worker/src/admin_api/index.ts
+++ b/worker/src/admin_api/index.ts
@@ -17,6 +17,7 @@ import db_api from './db_api'
 import ip_blacklist_settings from './ip_blacklist_settings'
 import ai_extract_settings from './ai_extract_settings'
 import { EmailRuleSettings } from '../models'
+import e2e_test_api from './e2e_test_api'
 
 export const api = new Hono<HonoCustomType>()
 
@@ -389,25 +390,6 @@ api.post("/admin/ip_blacklist/settings", ip_blacklist_settings.saveIpBlacklistSe
 api.get("/admin/ai_extract/settings", ai_extract_settings.getAiExtractSettings);
 api.post("/admin/ai_extract/settings", ai_extract_settings.saveAiExtractSettings);
 
-// Test-only endpoint for seeding emails. MUST NOT be enabled in production.
-api.post('/admin/test/seed_mail', async (c) => {
-    if (!getBooleanValue(c.env.E2E_TEST_MODE)) {
-        return c.text("Not available", 404);
-    }
-    const { address, source, raw, message_id } = await c.req.json();
-    if (!address || !raw) {
-        return c.text("address and raw are required", 400);
-    }
-    if (raw.length > 1_000_000) {
-        return c.text("raw content too large", 400);
-    }
-    if (message_id && message_id.length > 255) {
-        return c.text("message_id too long", 400);
-    }
-    const msgId = message_id || `<e2e-${Date.now()}@test>`;
-    const { success } = await c.env.DB.prepare(
-        `INSERT INTO raw_mails (message_id, source, address, raw, created_at)`
-        + ` VALUES (?, ?, ?, ?, datetime('now'))`
-    ).bind(msgId, source || address, address, raw).run();
-    return c.json({ success });
-});
+// E2E test endpoints
+api.post('/admin/test/seed_mail', e2e_test_api.seedMail);
+api.post('/admin/test/receive_mail', e2e_test_api.receiveMail);