If you can sync your email when the firewall is turned off, you'll need to allow the Mail and Calendar apps through the firewall. Windows Defender Security Center is free security software that's included with Windows 10. If you haven't installed alternative security software, you should temporarily turn off Windows Defender Security Center. Test other Office 365 Sync Errors Fix programs or websites to be sure Outlook is the only problem.

Method 4: Recreating the Outlook Profile

If two-factor authentication is turned on for your account, you'll need to create an app password for that account. An app password is used instead of your normal account password for apps Outlook Not Sending or Receiving Email that don't support two-factor authentication. Before you begin, make sure that your device has the latest operating system and app updates. Try the general troubleshooting solutions in Troubleshooting Mail and Calendar apps for Windows 10. Once you have completed the steps to fix Outlook sync errors, kindly check if the error has been fixed or not.

Check the connectivity to your email server

• This software also has a splitter option to split large-sized PST files into smaller ones, helping users prevent oversized PST file issues.
• You'll also receive a mail (to the alternate email and to your admin email) from Microsoft 365 that indicates your tenant has encountered directory synchronization errors.
• It is possible for a corrupted Outlook profile to impede synchronization.
• If you're using an Outlook.com, Microsoft 365, or Exchange account, you won't have advanced mailbox settings unless the account was set up using advanced setup.
• I’m at wits end and Microsoft stopped helping me because they feel the problem is on our end.
• In some cases setting up a new computer replacement was the only option to fix these odd Outlook Sync issues.
• Here is the strange part I tried to remove the computer from the domain and have Outlook run from a local account for a few days.

You'll also receive a mail (to the alternate email and to your admin email) from Microsoft how to fix Outlook not opening today 365 that indicates your tenant has encountered directory synchronization errors. For details see Identify directory synchronization errors in Microsoft 365. I still have it turned on on my laptop and it has not shown any issues yet.

Methods to fix Microsoft Outlook syncing error

To solve your Outlook issues, download the application from the Microsoft website and follow the directions. If I check the sync log I see a lot of sync errors for Inbox, sent items and a few other folders. The most common cause of an out-of-date account is an incorrect password. In the notification bar at the top of the app, select Fix account. If your password is incorrect, you'll see a message asking you to update your password.

Microsoft Outlook Sync issues

I’ve tried the Microsoft office uninstall tool provided by Microsoft (which deletes more items then just control panel uninstall). Below are the steps I’ve taken to try to resolve this issue. Two-factor authentication helps protect your account by making it more difficult for someone else to sign in. It verifies your identity using your password and a contact method (also known as security info). Outlook will show as connected to Exchange but is not receiving any new email. This can happen for days at a time, and then disappear for a day or 2, only to appear again.