Authentication fails when email address and UPN do not match

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I have no issues in Outlook 365 with being a global mailbox not updating on IMAP admin and having modern authentication with multi-factor authentication. If you have an issue that's not listed in this article, go to the following Microsoft TechNet wiki page. The wiki page lists other known issues and workarounds. Since Microsoft recently demanded OAuth2 authentication, I've been trying everything I found here and at Microsoft, but every 'help' webpage to setup Hotmail and Thunderbird seem badly outdated. If the error you are encountering is not listed, please create a ticket on our Email and Calendar Help page for assistance. iOS Mail Some users on macOS 10.14 have experienced issues logging back into Mac Mail after Modern Auth is applied to their accounts. Specifically, after successfully responding to the Duo prompt, the pop-up window will remain blank except for a spinning icon and never finish adding the account to the application. This issue has been resolved by having users connect to the UO VPN when initially setting up their account with Mac Mail. After logging in successfully once while connected to the VPN, any removing or re-adding of the account again to Mac Mail should not need the VPN. In many cases, simply removing the account from the application and re-adding the account using the standard Sign In method will resolve any issues being experienced when Modern Authentication is first turned on for an account. Please note that this can take a significant amount of time, depending on the size of your account and your other connected applications (Contacts, Calendar, etc). Outlook 365 Won't Prompt for Modern Authentication Microsoft will soon phase out Basic Authentication and replacing it with Modern Authentication. This is due to Modern Authentication's ability to support multi-factor authentication (such as Duo), which is better for information security. When this change goes into effect, any email application that uses Basic Authentication may not work properly. This article contains information about how to troubleshoot problems that affect the ability to sign in to Microsoft Office 2016 guide to Office 365 sign-in errors apps and Microsoft Office 2013 apps that are enabled for modern authentication. Once I added the AlwaysUseMSOAuthForAutodiscover value, it popped up the modern auth prompt and worked perfectly.UO email accounts set up in Mac Mail prior to the Modern Auth update will continue to work, provided the device is running macOS 10.14 or newer.Is there some kind of setting within O365 that’s forcing Outlook to use basic authentication ?It does look llike a one-time thing to switch it on.Microsoft will soon phase out Basic Authentication and replacing it with Modern Authentication.My concern is that MS will force modern authentication soon, and switch off basic authentication.I’ve just switched on Modern Authentication in Office 365, following on from Microsoft’s recommendation.To resolve this issue, set up AD FS to use forms-based authentication as the secondary form of authentication. Related Articles ( To resolve this issue, set up AD FS to use forms-based authentication as the secondary form of authentication. To do this, follow the appropriate steps for the version that you use. In certain AD FS configurations, the administrator may not have forms-based authentication enabled on the AD FS server. This prevents Windows clients that are running Office from logging in as required by the authentication process. Get email updates Consider trying this while connected to a wired or wireless network (instead of a cellular network) to increase speeds and avoid hitting data limitations. UO email accounts set up in Mac Mail prior to the Modern Auth update will continue to work, provided the device is running macOS 10.14 or newer. If issues are encountered, it is advised to first re-setup the account in Mac Mail. Removing and re-adding the account using the standard Sign In method will resolve this repair corrupted OST in Outlook error. My concern is that MS will force modern authentication soon, and switch off basic authentication. Outlook 2021 and Modern Authentication not working Create your account and connect with a world of communities. Once I added the AlwaysUseMSOAuthForAutodiscover value, it popped up the modern auth prompt and worked perfectly. I’ve just switched on Modern Authentication in Office 365, following on from Microsoft’s recommendation.