Outlook 2016 doesn't accept password or app password

This is exactly what I have asked before: Does outlook.com support EAS connection with OAuth for PERSONAL accounts? And I did not get an answer from both, David and Gabriel. I was not able to find any documentation from microsoft that cleary states this.

As you already mentioned I also found out that EWS will go EOL in the near future, but not EAS.

It would be very helpful to have an overview over what protocols are supported (with oauth) for personal accounts with/without M365 subscription.

Just as a reminder: We all want to have a protocol/connection type that supports oauth AND have at least eMail, calendar and contacts synch. Of course all data supported by EAS would be nice.

This page says to Switch to Outlook.com/Exchange Syncing but this is how all my outlook accounts were connected (via Outlook 2013). Yesterday I couldn't get into one of my accounts because of the CONSTANT credentials pop up so I deleted it & re-added it. It wouldn't open so I had to delete & re-add it again today & it is automatically connecting via IMAP - which the guidance says to avoid.
Honestly, this is so frustrating & I do feel Microsoft have created this problem to force people into either paying stupid money or downloading the privacy nightmare that is new Outlook.

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.

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?

Hi there - Yes, this is not something that is unique to Microsoft or any one email provider. This is common and many across the industry are moving this direction. I can't speak to what every provider is doing, but most will be removing the support for app passwords as well because it would leave the same security level of basic auth. It still is prime for abuse and attacks.

While the New Outlook is one option, you have others options as well. Sticking within the Outlook family you can upgrade to Outlook 2021 which does indeed support OAuth when syncing Outlook.com, get a Microsoft 365 Subscription that has the latest version of Outlook. Or you can use the web experience at outlook.com.

If those aren't viable options for you other third party mail solutions do indeed support OAuth against Outlook.com