Outlook 2016 doesn't accept password or app password

All you need to know:

Modern Authentication Methods now needed to continue syncing Outlook Email in non-Microsoft email apps https://support.microsoft.com/en-gb/office/modern-authentication-methods-now-needed-to-continue-syncing-outlook-email-in-non-microsoft-email-apps-c5d65390-9676-4763-b41f-d7986499a90d

Basic Authentication interim experience

Until September 16th, users signing into Outlook.com through Basic Authentication may experience recurring password prompts in Outlook and other third-party email applications. This is a known issue. After September 16th, users attempting to connect their Microsoft accounts through Basic Authentication will fail to do so.

The following versions of Outlook Desktop do not support Modern Authentication for Outlook.com:

Outlook 2007, Outlook 2010, Outlook 2013, Outlook 2016 MSI, Outlook 2019 LTSC. Any release of Outlook Desktop with a version less than 11601.10000 does not support Modern Authentication for Outlook.com.

I posted before that even Outlook 365 desktop doesn't work reliably for Hotmail.com account despite of what they are saying. I was getting issues like this as well but in Outlook's error message. Windows, Office, Teams.... there is not one non-buggy software. MS keep adding bloatware and unwanted features into every product. All of us are Microsoft's QA because they no longer have structured QA of their own. I am in the process of moving everything off Windows and going to Linux, so if the access for Thunderbird is not fixed, I will probably need to drop even more stuff off Microsoft ecosystem. The ability to run a few Win32 legacy apps is not enough to constantly live with these issues and endless concerns about privacy.

This is timely. I'm just in the process of transitioning from Outlook 2007 to Thunderbird in the expectation that it would fix the login issues :-(

I added some sandboxing ability around Outlook for Android, in addition to disabling all of its permissions, so Outlook only manages and touches app-local data. I don't want to share too much because the MS folks on this thread will probably feed the information back to their developers that may lead to ways to circumvent these methods.

By the way, I saw another post saying Basic Auth will be disabled by 9/15/2024 for the personal accounts, so we are 3 months away. Either move all your data off Microsoft system, or starting getting alternative clients ready.

Can you give us a hint as to what you've used for your "containment field", please?

Sounds useful as a temporary method for accessing this data... :)