outlook 2016 unable to connect to mail.office 365

If Office didn't see WAM running, there was no automatic fall back to leverage ADAL. This is similar to what occurred 2018 Q4 / 2019 Q1 when Office updated its authentication mode by leveraging WAM on Win10 machines not yet running v1809. Office apps can still run, even if the silent login fails, except Outlook because it still needs to login to Exchange Online. Recall when running O365 setup, and you get the prompt to sign into cloud, then after, it does the silent login. Office apps with their licenses sourced in the O365 Cloud authenticate there each time you launch one of the apps. That's your clue that the issue is not with Outlook / Exchange, but with the O365 client. They should show connections to the Sharepoint and OneDrive for Business sites tied to your O365 Cloud account. Check the Account settings (File tab > Account) in any Office app - Word, Excel, Powerpoint - and see the Connected Services section. This is not an issue with Outlook, but with the Office 365 desktop client. It's less disruptive than disabling WAM entirely. This feature isn't available for Microsoft 365 Government, Microsoft 365 operated by 21Vianet, or Microsoft 365 Germany.There's a simpler workaround by removing two Binary String entries under the 'Identity' subkey. This feature requires a Microsoft 365 administrator account. Select Run Tests: Outlook User Connectivity to download and run the diagnostic. The diagnostics perform automated checks to detect issues and provide possible solutions to fix them. There are Microsoft diagnostics that you can run to troubleshoot connectivity issues. For Windows Update instructions, see Windows Update: FAQ. Run Windows Update to make sure that you have the latest updates for Outlook and other desktop applications for Microsoft 365.

If your Outlook client software or Windows operating system software is out of date, you might have problems sending and receiving email. If you're an admin with multiple users reporting problems, you also should check for service issues with Microsoft 365. Out-of-date software and corrupted Outlook profiles are two of the most common issues that can prevent you from sending and receiving email. Need more help? Contact support for business products - Admin Help

Let us fix your issue Support and Recovery Assistant for Microsoft 365 If our automated tool can't fix your issue, or you'd like to fix it yourself, see the next section. We can diagnose and fix several common Outlook connectivity issues for you. Let us fix your Outlook connection problems for you

If you're looking for help with Outlook for Mac, check Outlook for Mac Help. If you're looking for help with, check Get help with.

Outlook 2016 unable to connect to mail.office 365