Fix Outlook for Mac Not Syncing: 7 Steps

If Outlook for Mac stops syncing email, calendar, or contacts, the fix is usually a combination of checking your internet connection, restarting the app, and re-authenticating your account. This article walks you through the most effective troubleshooting steps, from simple restarts to rebuilding your Outlook profile, so you can get back to a working inbox.

Why Outlook for Mac Stops Syncing

Outlook for Mac relies on a constant connection to your mail server (Microsoft 365, Exchange, Gmail, or IMAP). Sync failures happen for several common reasons:

Network issues: A weak Wi-Fi signal, VPN, or firewall can block Outlook’s connection to the server.
Account authentication expired: Passwords or OAuth tokens can expire, especially after a password change or a security policy update.
Outlook app glitches: The app itself may have a stuck process or a corrupted cache.
Server-side problems: Occasionally, the mail server (like Microsoft 365) has an outage.
Add-ins or plugins: A third-party add-in can interfere with sync.

Before You Start: Quick Checks

These take less than a minute and often solve the problem:

Check your internet connection by loading a website in Safari.
If you use a VPN, disconnect it temporarily and try syncing.
Look at the status bar at the bottom of the Outlook window. If it says “Disconnected” or “Trying to connect,” that points to a network or server issue.

Step-by-Step Fixes

1. Restart Outlook and Your Mac

A simple restart clears temporary glitches. Quit Outlook completely (Cmd+Q), then reopen it. If that doesn’t help, restart your Mac. This refreshes network connections and clears memory issues.

2. Toggle Airplane Mode or Wi-Fi

Sometimes the network stack gets stuck. Turn off Wi-Fi, wait 10 seconds, then turn it back on. If you’re on a corporate network, try switching from Wi-Fi to Ethernet (or vice versa) to see if the issue is specific to one connection.

3. Check Your Account Password and Authentication

If your password changed recently, Outlook may be using the old one. Go to Outlook > Preferences > Accounts, select your account, and click Advanced. Then click Delete Account and re-add it. You’ll be prompted to sign in again. For Microsoft 365 accounts, this will use OAuth (modern authentication). For IMAP accounts, you’ll enter the password manually.

4. Force a Manual Sync

In the main Outlook window, press Cmd+Option+K to force a send/receive. Watch the status bar to see if it starts syncing. If it still doesn’t, try clicking the folder name at the top of the folder list and selecting Update Folder.

5. Disable Problematic Add-ins

Add-ins can cause sync loops. Go to Outlook > Preferences > Add-ins. Disable all third-party add-ins, then restart Outlook. If syncing works, re-enable them one by one to find the culprit.

6. Rebuild the Outlook Database

If the above fail, the local database may be corrupted. Hold Option and click the Outlook icon in the Dock (or open Outlook from the Applications folder while holding Option). A window will appear asking to rebuild the database. This can take a while, but it preserves your data. It’s a safe operation—it doesn’t delete emails, but it may take time to re-index.

7. Create a New Outlook Profile

As a last resort, create a fresh profile. Go to Outlook > Preferences > General, click Manage Profiles, then click the + to add a new profile. Set it as default, then re-add your account. This gives you a clean slate. You can switch back to your old profile later if needed.

Common Sync Errors and What They Mean

You might see specific error messages. Here’s what they usually mean:

“Cannot connect to the server” – Network or server issue. Check your internet and the service status page for your provider.
“The password is incorrect” – Even if you think it’s right, re-enter it. For OAuth accounts, you may need to sign in again in a browser window.
“The operation could not be completed” – Generic error. Often fixed by a restart or rebuilding the database.
“Your mailbox is temporarily unavailable” – Server-side issue. Wait and try again.

When It’s a Server Problem

Sometimes the issue isn’t on your Mac. If you can access your email via a web browser (like Outlook on the web or Gmail in a browser), but Outlook can’t sync, the problem is likely local. If you can’t access it via the web either, check the service status page for your email provider. For Microsoft 365, visit the Microsoft 365 Service Health dashboard. For Gmail, check the Google Workspace Status Dashboard. If there’s an outage, you’ll just have to wait.

Preventing Future Sync Issues

Keep Outlook for Mac updated (usually via the Microsoft AutoUpdate tool).
Keep macOS updated.
Avoid using multiple devices with the same account simultaneously if you experience conflicts.
If you use a VPN, configure it to allow Outlook traffic.
Periodically restart your Mac to clear memory leaks.

Frequently Asked Questions

Why does Outlook for Mac show “Disconnected”?

This means Outlook cannot reach the mail server. Check your internet connection, try toggling Wi-Fi, and verify that you can access your email via a web browser. If the web works, restart Outlook or rebuild the database.

Will rebuilding the database delete my emails?

No. Rebuilding the database re-indexes your local cache, but your emails are still stored on the server. You may lose local drafts or cached items that haven’t synced yet, but that’s rare. Always back up important local data before doing this.

How do I force a full sync in Outlook for Mac?

Press Cmd+Option+K to force a send/receive. If that doesn’t work, go to Outlook > Preferences > Accounts, select your account, and click Advanced, then click Sync and choose “All” for the sync window.

Why is my calendar not syncing but email is?

This can happen if the calendar folder is not selected for sync. In Outlook > Preferences > Accounts, select your account, click Advanced, and ensure “Calendar” is checked under “Folders to sync.” Also, check if you have multiple calendars and the correct one is selected.

Does Outlook for Mac support OAuth (modern authentication)?

Yes, for Microsoft 365 and Outlook.com accounts, Outlook for Mac uses OAuth. For Gmail, it also uses OAuth. If you have an older account that uses basic authentication, you may need to switch to an app password if your provider requires it.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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