Windows Mail App Not Syncing
Quick answer: The classic Windows Mail & Calendar app was officially retired by Microsoft at the end of 2024 and can no longer send or receive email at all — this isn't a bug to troubleshoot, it's a sign you need to switch to the new Outlook for Windows app instead.
Important update: Microsoft ended support for the built-in Windows Mail and Calendar app on December 31, 2024. Past that date, the app can no longer send or receive new email, even though it may still open and show old, previously-downloaded messages. If you're on Windows 10 or 11 and the app has genuinely stopped working rather than just acting up, this is almost certainly why — the steps below won't fix that, because the app itself has been intentionally shut off from sending mail. The real fix is switching to the new Outlook app, which comes pre-installed on current Windows 11 and is available as a free download for Windows 10. It can import your existing accounts and local data automatically.
The troubleshooting below is still useful if you're on an older system that hasn't been affected yet, or if the app opens and shows old mail but something else is specifically off — but if send/receive has stopped working entirely and it's been a while since you last checked, read the notice above first.
1. Force a manual sync
- Open Mail.
- Click the sync icon at the top of the message list, or press F5.
2. Check sync settings for the account
- Settings (gear icon, bottom left) → Manage Accounts → select the account.
- Click "Change mailbox sync settings" and confirm "Download email from" isn't set to some narrow window, and sync frequency isn't set to Manual.
3. Check Windows' own background app settings
- Windows Settings → Apps → Mail and Calendar → confirm it's allowed to run in the background.
- Settings → Network & internet → confirm you're not on a connection marked "Metered," which throttles background sync without much warning.
4. Remove and re-add the account
- Settings → Manage Accounts → select the account → Delete account from this device.
- Restart Mail, then add the account again.
5. Reset the Mail app
If this keeps happening across multiple accounts, the app itself may need a reset.
- Windows Settings → Apps → Installed apps → find Mail and Calendar → Advanced options.
- Click Reset. Just know this signs you out of everything in the app — you'll need to re-add each account after.
Honestly, a lot of people find the built-in Mail app less reliable for large or old mailboxes than a dedicated client like Outlook or Thunderbird. If sync issues keep coming back, switching apps is a completely reasonable move.
App won't open, or keeps crashing rather than just failing to sync? See our guide on Windows Mail app won't open or keeps crashing.