diff --git a/content/utils.js b/content/utils.js
index 3b8f0f5..7eab2e4 100644
--- a/content/utils.js
+++ b/content/utils.js
@@ -15,6 +15,7 @@ function detectScriptSource({
     || hostname.endsWith('.mail.163.com')
     || hostname === 'webmail.vip.163.com'
     || hostname === 'mail.126.com'
+    || hostname.endsWith('.mail.126.com')
   ) return 'mail-163';
   if (hostname === 'mail.google.com') return 'gmail-mail';
   if (hostname === 'www.icloud.com' || hostname === 'www.icloud.com.cn') return 'icloud-mail';
diff --git a/tests/content-utils.test.js b/tests/content-utils.test.js
index 0ea69ca..e3a11d0 100644
--- a/tests/content-utils.test.js
+++ b/tests/content-utils.test.js
@@ -64,3 +64,19 @@ return { detectScriptSource };
     'mail-163'
   );
 });
+
+test('detectScriptSource maps 126 mail subdomains to the shared 163 mail source', () => {
+  const bundle = [extractFunction('detectScriptSource')].join('\n');
+  const api = new Function(`
+${bundle}
+return { detectScriptSource };
+`)();
+
+  assert.equal(
+    api.detectScriptSource({
+      url: 'https://app.mail.126.com/js6/main.jsp',
+      hostname: 'app.mail.126.com',
+    }),
+    'mail-163'
+  );
+});