diff --git a/background/mail-2925-session.js b/background/mail-2925-session.js
index 410fa97..4db55db 100644
--- a/background/mail-2925-session.js
+++ b/background/mail-2925-session.js
@@ -584,6 +584,18 @@
         await failMailboxSession(`2925：${actionLabel}失败，登录后仍未进入收件箱。`);
       }
 
+      if (!account) {
+        await addLog('2925：未触发自动登录，继续复用当前已登录会话。', 'info');
+        return {
+          account: null,
+          mail: getMail2925MailConfig(),
+          result: {
+            ...result,
+            usedExistingSession: true,
+          },
+        };
+      }
+
       await patchMail2925Account(account.id, {
         lastLoginAt: Date.now(),
         lastError: '',
diff --git a/tests/background-mail2925-entry-behavior.test.js b/tests/background-mail2925-entry-behavior.test.js
index cd9cc07..ec75def 100644
--- a/tests/background-mail2925-entry-behavior.test.js
+++ b/tests/background-mail2925-entry-behavior.test.js
@@ -426,3 +426,69 @@ test('ensureMail2925MailboxSession stops when mailbox page email mismatches and
   assert.equal(stopCalls.length, 1);
   assert.match(stopCalls[0].logMessage, /与目标账号 target@2925\.com 不一致/);
 });
+
+test('ensureMail2925MailboxSession does not crash when mailbox page is reused but top email cannot be detected', async () => {
+  let currentState = {
+    autoRunning: false,
+    mail2925UseAccountPool: false,
+    mail2925Accounts: [],
+    currentMail2925AccountId: null,
+  };
+  let sendCalls = 0;
+
+  const manager = api.createMail2925SessionManager({
+    addLog: async () => {},
+    broadcastDataUpdate: () => {},
+    chrome: {
+      tabs: {
+        get: async () => ({ id: 9, url: 'https://2925.com/#/mailList' }),
+      },
+      cookies: {
+        getAll: async () => [],
+        remove: async () => ({ ok: true }),
+      },
+      browsingData: {
+        removeCookies: async () => {},
+      },
+    },
+    ensureContentScriptReadyOnTab: async () => {},
+    findMail2925Account: mail2925Utils.findMail2925Account,
+    getMail2925AccountStatus: mail2925Utils.getMail2925AccountStatus,
+    getState: async () => currentState,
+    isAutoRunLockedState: () => false,
+    isMail2925AccountAvailable: mail2925Utils.isMail2925AccountAvailable,
+    MAIL2925_LIMIT_COOLDOWN_MS: mail2925Utils.MAIL2925_LIMIT_COOLDOWN_MS,
+    normalizeMail2925Account: mail2925Utils.normalizeMail2925Account,
+    normalizeMail2925Accounts: mail2925Utils.normalizeMail2925Accounts,
+    pickMail2925AccountForRun: mail2925Utils.pickMail2925AccountForRun,
+    reuseOrCreateTab: async () => 9,
+    sendToMailContentScriptResilient: async () => {
+      sendCalls += 1;
+      return {
+        loggedIn: true,
+        currentView: 'mailbox',
+        mailboxEmail: '',
+      };
+    },
+    setPersistentSettings: async (payload) => {
+      currentState = { ...currentState, ...payload };
+    },
+    setState: async (updates) => {
+      currentState = { ...currentState, ...updates };
+    },
+    throwIfStopped: () => {},
+    upsertMail2925AccountInList: mail2925Utils.upsertMail2925AccountInList,
+  });
+
+  const result = await manager.ensureMail2925MailboxSession({
+    accountId: null,
+    forceRelogin: false,
+    allowLoginWhenOnLoginPage: false,
+    expectedMailboxEmail: 'target@2925.com',
+    actionLabel: '步骤 4：确认 2925 邮箱登录态',
+  });
+
+  assert.equal(sendCalls, 1);
+  assert.equal(result.account, null);
+  assert.equal(result.result.usedExistingSession, true);
+});
diff --git a/tests/sidepanel-mail2925-base-email.test.js b/tests/sidepanel-mail2925-base-email.test.js
index 8b17251..f27d503 100644
--- a/tests/sidepanel-mail2925-base-email.test.js
+++ b/tests/sidepanel-mail2925-base-email.test.js
@@ -186,6 +186,7 @@ const inputTempEmailBaseUrl = { value: '' };
 const inputTempEmailAdminAuth = { value: '' };
 const inputTempEmailCustomAuth = { value: '' };
 const inputTempEmailReceiveMailbox = { value: '' };
+const inputTempEmailUseRandomSubdomain = { checked: false };
 const inputAutoSkipFailures = { checked: false };
 const inputAutoSkipFailuresThreadIntervalMinutes = { value: '0' };
 const inputAutoDelayEnabled = { checked: false };