The other solution to fix Outlook sync issues is recreating Microsoft Outlook profile. Follow each step carefully to resolve synchronization errors. Sometimes an error appears in the Mail and Calendar apps when credential loop in Microsoft 365 the apps try to sync new email or calendar events. We’ve had sync issues with employees from time to time however, re doing the mail profile or wiping the Windows profile usually fixes it.

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 connection status shows disconnected is not from a trusted certifying authority."

Check the connectivity to your email server

• We have shared five manual methods in this blog to resolve the Outlook syncing errors.
• The client has a computer off the domain at home that his work email is tied to and he has never had any of these issues in Cache mode with that device.
• Once the client started using Outlook again after some time has passed the issue had come back.
• If it does, you might need to include Outlook exceptions in the settings of your security program.
• When they go back to the message and press send they get an error that the message has been deleted.
• After these instructions, ensure the sync settings are correct and check everything is working well.
• Always make sure your profile and settings are set up correctly, your software is up to date, and your connection is steady.
• The other solution to fix Outlook sync issues is recreating Microsoft Outlook profile.

You'll also receive a mail (to the alternate email and to your admin email) from Microsoft Fix Outlook and Office365 Sync Issues 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

In some cases setting up a new computer replacement was the only option to fix these odd Outlook Sync issues. Outlook’s ability to connect to the mail server may be blocked by firewalls or antivirus software. After you’re satisfied, turn off your firewall or antivirus program for a while. If it does, you might need to include Outlook exceptions in the settings of your security program. Users can also convert OST files into various file formats, including PST, HTML, EML, MSG, vCard, etc.

Microsoft Outlook Sync issues

To make sure there are no issues, click Test Account Settings to test the connection. It is possible for a corrupted Outlook profile to impede synchronization. Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support. If the problems do not occur in safe mode, its most likely an add-in causing grief. I’ve been in contact with Microsoft they had me migrate his account\data to another server this did not fix it.