Why macOS Mail says “your account stopped syncing”
Short answer: macOS Mail uses OAuth 2.0 — a secure token-based authentication system — to access Gmail and Outlook without storing your password on the Mac. When the token expires, when you change your account password, or when your IT administrator revokes access, Mail cannot connect to the server and shows this error. The token is the access key, not your password — re-authenticating issues a fresh key in under two minutes. This is purely a software credential issue; no hardware is involved.
How to fix macOS Mail account sync errors
Step 1: Re-authenticate in System Settings Internet Accounts
Open System Settings → Internet Accounts (called Internet Accounts in older macOS). Click the Gmail or Microsoft Exchange / Outlook account that has stopped syncing. If a Sign in or Re-enter Password button is visible, click it. A browser sheet appears — sign in with your Google or Microsoft credentials and approve access. macOS stores a fresh OAuth token and Mail resumes syncing within a few minutes. This is the correct fix for the majority of cases — do not attempt a Mail reinstall or macOS update before trying this first.
Step 2: Remove and re-add the account
If the re-authenticate button is not visible, or if it fails silently, remove the account entirely and add it fresh. In System Settings → Internet Accounts, select the problematic account and click the minus (–) button to remove it. For IMAP accounts (Gmail, Outlook, iCloud), this does not delete emails from the server. It removes only the local cache on your Mac. After removing, click the plus (+) button, select the provider, and sign in again. Mail redownloads messages from the server — this takes a few minutes on large inboxes.
Step 3: Delete corrupted Keychain token entries
If Mail keeps prompting for your password in a loop even after re-authenticating, a corrupted token is stored in the macOS Keychain. Open Keychain Access, search for imap.gmail.com or outlook.office365.com depending on your provider, and delete all entries for that server. Also search for your email address and delete any tokens or internet passwords associated with it. Then go back to Internet Accounts and sign in fresh. See the macOS update issues fix guide if the Mail error appeared immediately after a macOS update — sometimes an update resets account configurations.
Step 4: The India angle — corporate Office 365 and two-factor authentication
Indian organisations — particularly IT companies in Hyderabad, Pune, and Bengaluru — frequently enforce conditional access policies on Microsoft 365 that require device management enrollment before allowing native mail clients. When your company changes its Intune or Azure AD policy, macOS Mail tokens get revoked for all non-enrolled devices simultaneously. If everyone in the office on a Mac suddenly cannot access Outlook, this is the cause, not a MacBook fault. Contact your IT administrator to either enroll the MacBook in device management or use the Outlook for Mac app directly, which handles conditional access more gracefully than the native Mail app. For personal Gmail, enabling two-step verification without re-authenticating Mail is the most common trigger we see from individual users.
When to call a repair service
When the error persists across all accounts and providers
If Mail cannot connect to any account — Gmail, Outlook, and iCloud all simultaneously failing — the issue is the macOS networking or security framework rather than individual account tokens. A fresh macOS reinstall resolves deep credential framework corruption. For corporate Microsoft 365 failures caused by a Conditional Access policy change, the fix is on the IT administrator's side — enrolling the MacBook in Intune device management or granting an exception in Azure AD. This does not require a repair shop visit; it is an IT administration task. Cost for macOS reinstall: ₹1,500–₹2,500 at a service centre. The ₹149 doorstep visit diagnoses whether it is a MacBook-side software problem or an organisation-side policy block before any commitment.
Step 4: Check for Mail app database corruption
If Mail resumed syncing but shows emails out of order, misses some messages, or spins indefinitely on "Checking for Mail", the local Envelope Index — the database Mail uses to display messages quickly — may be corrupted. To rebuild it: quit Mail, open Finder, press Command + Shift + G, navigate to ~/Library/Mail/V10 (the folder name varies by macOS version), and delete the file named Envelope Index. When Mail reopens, it rebuilds the index from the server, which can take 10–30 minutes on large inboxes. Do not interrupt Mail during this rebuild.
A note from the LRW Engineer Team
We see this complaint most often the day after a company-wide Microsoft 365 policy change or a Google Workspace security audit. The fix is always in System Settings → Internet Accounts — the MacBook hardware is never the cause. If your organisation is on Microsoft 365 and has recently enabled Conditional Access or Intune enrollment requirements, the Outlook for Mac app (available free from the Mac App Store) handles these policies far more gracefully than the native Mail app and is often the best long-term solution for corporate accounts. The Apple MacBook service page covers our configuration and software diagnostic services for M-series and Intel models.