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 Fix Outlook and Office365 Sync Issues programs or websites to be sure Outlook is the only problem.

Method 4: Recreating the Outlook Profile

However once I joined this computer back to the domain and let it sit for a few days it was also working fine. Once the client started using Outlook again after some time has passed the issue had come back. I’ve tried to set cache mode from 1 year all the way down to a few days. If your password isn't the problem, you might have a certificate error. If so, you'll see a message that says, "There is a problem with the server's security certificate. The security certificate Fix Outlook and Office 365 Errors 2025 is not from a trusted certifying authority."

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.
• Apart from this, we also discuss the Shoviv OST to PST Converter Tool, a professional way to repair, recover, and convert Outlook data files.
• I’m at wits end and Microsoft stopped helping me because they feel the problem is on our end.
• 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.
• 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.

When the user is signed into their mobile app, webmail, or the Reset cached exchange Mode Windows Mail app, they are able to receive email perfectly fine with those. The issue is occurring only in the Outlook program installed on Windows. To update from Azure AD Sync to Microsoft Entra Connect, see the upgrade instructions.

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.