Outlook 2016 doesn't accept password or app password

Not IMAP or POP3 because I want to sync email and calendar. 2FA/MFA enabled on the accounts. I used auto discovery to add the account and I see the auto discovery process created an account as EAS account. I get the initial OAuth popped authentication window, via browser, and answered. Setup is complete, and it actually started to build .OST again... and minutes or hours later, bam, authentication prompt. I also tried setup manually and directly point the server address to eas.outlook.com, and will eventually lead to the same behavior and issue.

I am not sure if you have read all the comments here. Multiple people have posted about similar experiences.

I read all of yours and Gabriel's comments, which is saying the issue is caused by people using Basic Auth and because MS is getting brute-force attacked, you have an algo to block authentication attempts if it senses the attempts resemble attack characteristics. I honestly don't believe you've gotten to the root cause of the issue.

Honestly, this issue exposes problems within MS. You have articles suggesting OAuth was not enabled by default on older Outlook versions, but can be enabled by regkeys, but turns out those are not true by your own account, "...after reviewing the code..." so quite frankly, many of us don't know what to believe or how deep to cast our doubts.

Are you using OAuth? Do you have details about your setup? Such as IMAP vs Outlook.com Sync?

Ideally I would recommend opening up an in app support ticket. That way the support agent can see details about how your accoutns are configured.

AnotherBug - We are not forcing you to move to the New Outlook for Windows. It is purely an option, just like you can adopt and use a later version of Outlook such as Outlook 2021, or Outlook that is included in Microsoft 365. For those that are looking for a free option, we are mentioning the new Outlook. If none of those meet your needs or requirements there is also additional 3rd party email clients which do indeed have the needed Modern Auth support. Such as Thunderbird, the Apple Mail app on Mac OS or iOS. We continue to support open standards like imap, pop, and smtp.

And... we continue to tell you that we are having this problem with almost all clients, Microsoft's or third-parties. How do you explain that? Can you address the comment I made about having issue with all common clients, including even Microsoft's own latest clients, "New Outlook" excluded? I already mentioned that Gmail for Android, Outlook for Android, Outlook from M365 are having the same issue....before I removed my account, even my iOS device was having this issue. Exactly what's the answer for that?

AnotherBug - We are not forcing you to move to the New Outlook for Windows. It is purely an option, just like you can adopt and use a later version of Outlook such as Outlook 2021, or Outlook that is included in Microsoft 365. For those that are looking for a free option, we are mentioning the new Outlook. If none of those meet your needs or requirements there is also additional 3rd party email clients which do indeed have the needed Modern Auth support. Such as Thunderbird, the Apple Mail app on Mac OS or iOS. We continue to support open standards like imap, pop, and smtp.

Thanks Omar for trying the new Outlook and getting all of your accounts added. If you have any feedback or anything at all please let us know. We are actively working to bring more functionality and address feedback and requests as they come in.

On the Ad front, yes if you do not have a Microsoft 365 subscription there will be ads, however if you have one you will not see ads in any of your accounts. Hope that helps.