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 after Windows update issues programs or websites to be sure Outlook is the only problem.

Method 4: Recreating the Outlook Profile

Here, we will discuss the Troubleshoot Office 365 Sync and Login Issues five manual methods to fix sync issues in Outlook or OWA. Before finding solutions, we suggest that users check their internet connection. Sometimes, Outlook sync issues can arise because of poor internet connection. If you are still facing this issue, kindly follow the solutions below to fix the sync issues in Outlook. Firewalls and antivirus software might prevent you from syncing your email and calendar events.

Check the connectivity to your email server

• We have resources to help you identify potential issues and fix them.
• I’ve been in contact with Microsoft they had me migrate his account\data to another server this did not fix it.
• Below are the steps I’ve taken to try to resolve this issue.
• Firewalls and antivirus software might prevent you from syncing your email and calendar events.
• This solution will be beneficial for users who are facing Outlook syncing issues because of corrupted PST or OST files.

You'll also receive a mail (to the alternate email and to your admin email) from Microsoft flush dns and re-sync outlook 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

I ran the PSTscan tool to check for anomalies on the OST file (which it found and repaired but the issue still occurs). However, with one particular client no matter what changes are made these sync issue still occur. We're sorry you're having problems with the Mail and Calendar apps for Windows 10. To fix the issue, please try each of the following solutions in order.

Microsoft Outlook Sync issues

Always make sure your profile and settings are set up correctly, your software is up to date, and your connection is steady. The causes of sync issues and local failures in Outlook are explained in this guide, along with practical troubleshooting and resolution techniques. You can extract and recover all of your mail items to a PST file using sophisticated OST File to PST Converter software if your OST file becomes unavailable or orphaned. Third-party firewalls or antivirus software might prevent you from syncing your email and calendar events. Check the software documentation to learn how to temporarily turn it off.