diff --git a/content/mail-2925.js b/content/mail-2925.js
index 0197ce7..404477c 100644
--- a/content/mail-2925.js
+++ b/content/mail-2925.js
@@ -11,10 +11,22 @@ if (!isTopFrame) {
 } else {
 
 let seenCodes = new Set();
+let seenCodeSessionKey = '';
+let seenCodesReadyPromise = null;
 
 async function loadSeenCodes() {
   try {
-    const data = await chrome.storage.session.get('seen2925Codes');
+    const data = await chrome.storage.session.get(['seen2925CodeState', 'seen2925Codes']);
+    const state = data?.seen2925CodeState || null;
+    if (state && typeof state === 'object') {
+      seenCodeSessionKey = String(state.sessionKey || '');
+      if (Array.isArray(state.codes)) {
+        seenCodes = new Set(state.codes);
+      }
+      console.log(MAIL2925_PREFIX, `Loaded ${seenCodes.size} seen codes for session ${seenCodeSessionKey || 'default'}`);
+      return;
+    }
+
     if (data.seen2925Codes && Array.isArray(data.seen2925Codes)) {
       seenCodes = new Set(data.seen2925Codes);
       console.log(MAIL2925_PREFIX, `Loaded ${seenCodes.size} previously seen codes`);
@@ -24,16 +36,46 @@ async function loadSeenCodes() {
   }
 }
 
-loadSeenCodes();
+seenCodesReadyPromise = loadSeenCodes();
 
 async function persistSeenCodes() {
   try {
-    await chrome.storage.session.set({ seen2925Codes: [...seenCodes] });
+    await chrome.storage.session.set({
+      seen2925Codes: [...seenCodes],
+      seen2925CodeState: {
+        sessionKey: seenCodeSessionKey,
+        codes: [...seenCodes],
+      },
+    });
   } catch (err) {
     console.warn(MAIL2925_PREFIX, 'Could not persist seen codes, continuing in-memory only:', err?.message || err);
   }
 }
 
+function buildSeenCodeSessionKey(step, payload = {}) {
+  const timestamp = Number(payload?.filterAfterTimestamp);
+  if (Number.isFinite(timestamp) && timestamp > 0) {
+    return `${step}:${timestamp}`;
+  }
+  return `${step}:default`;
+}
+
+async function ensureSeenCodesSession(step, payload = {}) {
+  if (seenCodesReadyPromise) {
+    await seenCodesReadyPromise;
+    seenCodesReadyPromise = null;
+  }
+
+  const nextSessionKey = buildSeenCodeSessionKey(step, payload);
+  if (seenCodeSessionKey === nextSessionKey) {
+    return;
+  }
+
+  seenCodeSessionKey = nextSessionKey;
+  seenCodes = new Set();
+  await persistSeenCodes();
+}
+
 chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
   if (message.type === 'POLL_EMAIL') {
     resetStopState();
@@ -473,6 +515,7 @@ async function refreshInbox() {
 }
 
 async function handlePollEmail(step, payload) {
+  await ensureSeenCodesSession(step, payload);
   const {
     senderFilters,
     subjectFilters,
diff --git a/tests/mail-2925-content.test.js b/tests/mail-2925-content.test.js
index ad54311..30df390 100644
--- a/tests/mail-2925-content.test.js
+++ b/tests/mail-2925-content.test.js
@@ -116,6 +116,7 @@ async function openMailAndDeleteAfterRead(item) {
   return item.id === 'new' ? 'Your ChatGPT code is 654321' : 'No code here';
 }
 
+async function ensureSeenCodesSession() {}
 function persistSeenCodes() {}
 function log() {}
 
@@ -199,6 +200,7 @@ async function openMailAndDeleteAfterRead(item) {
   return item.text;
 }
 
+async function ensureSeenCodesSession() {}
 function persistSeenCodes() {}
 function log() {}
 
@@ -224,6 +226,58 @@ return {
   assert.deepEqual(api.getReadAndDeleteCalls(), ['mail-1']);
 });
 
+test('ensureSeenCodesSession resets tried codes only when a new verification step session starts', async () => {
+  const bundle = [
+    extractFunction('buildSeenCodeSessionKey'),
+    extractFunction('ensureSeenCodesSession'),
+  ].join('\n');
+
+  const api = new Function(`
+let seenCodes = new Set(['111111']);
+let seenCodeSessionKey = '';
+let seenCodesReadyPromise = Promise.resolve();
+const persisted = [];
+
+async function persistSeenCodes() {
+  persisted.push({
+    sessionKey: seenCodeSessionKey,
+    codes: [...seenCodes],
+  });
+}
+
+${bundle}
+
+return {
+  ensureSeenCodesSession,
+  getSeenCodes() {
+    return [...seenCodes];
+  },
+  getSessionKey() {
+    return seenCodeSessionKey;
+  },
+  getPersisted() {
+    return persisted.slice();
+  },
+};
+`)();
+
+  await api.ensureSeenCodesSession(4, { filterAfterTimestamp: 1000 });
+  assert.equal(api.getSessionKey(), '4:1000');
+  assert.deepEqual(api.getSeenCodes(), []);
+
+  await api.ensureSeenCodesSession(4, { filterAfterTimestamp: 1000 });
+  assert.deepEqual(api.getPersisted(), [
+    { sessionKey: '4:1000', codes: [] },
+  ]);
+
+  await api.ensureSeenCodesSession(8, { filterAfterTimestamp: 2000 });
+  assert.equal(api.getSessionKey(), '8:2000');
+  assert.deepEqual(api.getPersisted(), [
+    { sessionKey: '4:1000', codes: [] },
+    { sessionKey: '8:2000', codes: [] },
+  ]);
+});
+
 test('openMailAndGetMessageText always returns to inbox after opening a 2925 message', async () => {
   const bundle = [
     extractFunction('returnToInbox'),