Incorrect Outlook settings can also be one of the reasons behind Outlook synchronization errors. The Support and Recovery Assistant, a tool provided by Microsoft, can identify and resolve common Outlook problems. It is capable of automatically mailbox not updating on IMAP identifying problems with account setups, sync, and other typical mistakes. To solve your Outlook issues, download the application from the Microsoft website and follow the directions. Outlook’s ability to connect to the mail server may be blocked by firewalls or antivirus software.

Turn off Windows Defender Security Center

If the size of your .ost file is close to the limit, you could try increasing the limit on your client, restart Outlook and see if there is any difference. flush DNS and Re-sync Outlook I’ve unchecked download shared folders when setting up a new Outlook profile. After performing these steps, Outlook’s all folders will be synced to the server. If this method doesn’t work for you, navigate to other solutions. Select the button below to launch a diagnostic in the Microsoft 365 admin center.

Check if two-factor authentication is turned on for your account

It is possible for a corrupted Outlook profile to impede synchronization. Test other programs or websites to be sure Outlook is the only problem. If the connection is poor, consider restarting your modem/router or moving to a more reliable network. 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 is not from a trusted certifying authority." Check with your email provider for instructions about how to create an app password for your email account.

Check Antivirus and Firewall Settings

• If you're using an Exchange account that requires advanced settings, you'll need to remove the account and add it again using advanced settings.
• After you’re satisfied, turn off your firewall or antivirus program for a while.
• In the notification bar at the top of the app, select Fix account.
• Windows Defender Security Center is free security software that's included with Windows 10.
• 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.
• This blog talks about the causes behind Outlook synchronization errors and a few solutions to fix Outlook sync issues.
• Tempted to create a Test Shared Mailbox, but thinking that wouldn't be an accurate test for inbound mail, etc. or just actually tested by the Users at all.
• We have shared five manual methods in this blog to resolve the Outlook syncing errors.
• However, I cannot find any reason why his account would do this only on our domain nothing is blocking our connection to Office 365.

If you can sync your email when the firewall is turned off, you'll need to allow the credential loop in Microsoft 365 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.

Free Methods to Remove Duplicate Items in Outlook 2016

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. I’ve been in contact with Microsoft they had me migrate his account\data to another server this did not fix it. I’ve tried the Microsoft office uninstall tool provided by Microsoft (which deletes more items then just control panel uninstall).