diff --git a/content/mail-163.js b/content/mail-163.js
index 547ea73..edab71b 100644
--- a/content/mail-163.js
+++ b/content/mail-163.js
@@ -377,12 +377,13 @@ function collectOpenedMailTextCandidates() {
   return texts.sort((a, b) => b.length - a.length);
 }
 
-function readOpenedMailText(item) {
+function selectOpenedMailTextCandidate(item, candidates = [], options = {}) {
   const subject = normalizeText(getMailSubjectText(item)).toLowerCase();
   const sender = normalizeText(getMailSenderText(item)).toLowerCase();
-  const candidates = collectOpenedMailTextCandidates();
+  const excludedSet = new Set((options.excludedTexts || []).map((value) => normalizeText(value)));
+  const allowExcludedFallback = options.allowExcludedFallback !== false;
 
-  const preferred = candidates.find((candidate) => {
+  const pickCandidate = (source) => source.find((candidate) => {
     const lower = candidate.toLowerCase();
     if (subject && lower.includes(subject)) {
       return true;
@@ -391,9 +392,20 @@ function readOpenedMailText(item) {
       return true;
     }
     return Boolean(extractVerificationCode(candidate) && /chatgpt|openai|verification|验证码|login code/i.test(lower));
-  });
+  }) || source[0] || '';
 
-  return preferred || candidates[0] || '';
+  const filteredCandidates = candidates.filter((candidate) => !excludedSet.has(normalizeText(candidate)));
+  const preferred = pickCandidate(filteredCandidates);
+  if (preferred || !allowExcludedFallback) {
+    return preferred;
+  }
+
+  return pickCandidate(candidates);
+}
+
+function readOpenedMailText(item, options = {}) {
+  const candidates = collectOpenedMailTextCandidates();
+  return selectOpenedMailTextCandidate(item, candidates, options);
 }
 
 async function returnToInbox() {
@@ -417,7 +429,8 @@ async function returnToInbox() {
 }
 
 async function openMailAndGetMessageText(item) {
-  const beforeText = readOpenedMailText(item);
+  const beforeCandidates = collectOpenedMailTextCandidates();
+  const beforeText = selectOpenedMailTextCandidate(item, beforeCandidates);
   if (typeof simulateClick === 'function') {
     simulateClick(item);
   } else {
@@ -427,7 +440,10 @@ async function openMailAndGetMessageText(item) {
   let openedText = '';
   for (let i = 0; i < 24; i += 1) {
     await sleep(250);
-    const candidate = readOpenedMailText(item);
+    const candidate = readOpenedMailText(item, {
+      excludedTexts: beforeCandidates,
+      allowExcludedFallback: false,
+    });
     if (!candidate) {
       continue;
     }
diff --git a/tests/mail-163-content.test.js b/tests/mail-163-content.test.js
index 34f3ec3..72f7bd6 100644
--- a/tests/mail-163-content.test.js
+++ b/tests/mail-163-content.test.js
@@ -147,6 +147,7 @@ test('readOpenedMailText prefers opened body content that contains the verificat
   const bundle = [
     extractFunction('normalizeText'),
     extractFunction('collectOpenedMailTextCandidates'),
+    extractFunction('selectOpenedMailTextCandidate'),
     extractFunction('readOpenedMailText'),
     extractFunction('extractVerificationCode'),
   ].join('\n');
@@ -194,6 +195,7 @@ test('openMailAndGetMessageText reads opened body text and returns to inbox', as
   const bundle = [
     extractFunction('normalizeText'),
     extractFunction('collectOpenedMailTextCandidates'),
+    extractFunction('selectOpenedMailTextCandidate'),
     extractFunction('readOpenedMailText'),
     extractFunction('returnToInbox'),
     extractFunction('openMailAndGetMessageText'),
@@ -262,6 +264,82 @@ return {
   assert.equal(api.isInInbox(), true);
 });
 
+test('openMailAndGetMessageText ignores stale pre-open text that contains an old code', async () => {
+  const bundle = [
+    extractFunction('normalizeText'),
+    extractFunction('collectOpenedMailTextCandidates'),
+    extractFunction('selectOpenedMailTextCandidate'),
+    extractFunction('readOpenedMailText'),
+    extractFunction('returnToInbox'),
+    extractFunction('openMailAndGetMessageText'),
+    extractFunction('extractVerificationCode'),
+  ].join('\n');
+
+  const api = new Function(`
+let stage = 'before';
+const oldText = 'OpenAI Your temporary ChatGPT login code. Ignore this old code 111111. '.repeat(10);
+const newText = 'OpenAI Your temporary ChatGPT login code. Your new code is 222222.';
+const mailItem = {
+  click() {
+    stage = 'after';
+  },
+};
+const inboxLink = {
+  click() {
+    stage = 'done';
+  },
+};
+
+function getMailSubjectText() {
+  return 'Your temporary ChatGPT login code';
+}
+
+function getMailSenderText() {
+  return 'OpenAI';
+}
+
+const document = {
+  querySelector(selector) {
+    if (selector === '.nui-tree-item-text[title="收件箱"], [title="收件箱"]') return inboxLink;
+    return null;
+  },
+  querySelectorAll(selector) {
+    if (selector === 'iframe') {
+      return [];
+    }
+    if (stage === 'before') {
+      return [{ innerText: oldText, textContent: oldText }];
+    }
+    if (stage === 'after') {
+      return [
+        { innerText: oldText, textContent: oldText },
+        { innerText: newText, textContent: newText },
+      ];
+    }
+    return [];
+  },
+  body: {
+    innerText: '',
+    textContent: '',
+  },
+};
+
+function findMailItems() {
+  return stage === 'done' ? [mailItem] : [];
+}
+
+async function sleep() {}
+
+${bundle}
+
+return { openMailAndGetMessageText, mailItem };
+`)();
+
+  const text = await api.openMailAndGetMessageText(api.mailItem);
+  assert.match(text, /222222/);
+  assert.doesNotMatch(text, /111111/);
+});
+
 test('handlePollEmail ignores same-minute old snapshot mail before fallback', async () => {
   const bundle = [
     extractFunction('normalizeText'),