Outlook 2016 doesn't accept password or app password

Gabriel,

Perhaps I'm missing something already written before (I'm not about to read and study all 76 pages of this hideous thread), but I begin to wonder if the issue here is LESS about your servers and more about how our Apps (Outlook 2013 and Outlook 2016) are dealing with messaging from your servers.

To refresh, I'm using OL 2013 with 1 (one) hotmail and 3 outlook accounts.
Like everyone else, I keep getting the password dialog boxes being fired.
However, the password dialog box being fired IN NO WAY means I'm not connected.
It might mean that, but usually this is only after some length of time has passed since I took some corrective action.
And by corrective action, I DO NOT MEAN ENTERING THE PASSWORD IN THE DIALOG BOX.

For me to come to this possible conclusion it's important to remember all these messages are being managed by my application (Outlook 2013).
These messages (dialogs boxes or status bar prompts, or ribbon buttons, or Windows alerts) are ALL being triggered by Outlook 2013.
NOT YOUR SERVERS.

AND, when I follow certain steps (within a reasonable time frame) I remain connected to your servers DESPITE the messaging from Outlook or Windows.

When I'm selected on one of the 4 accounts, and the "SEND/RECEIVE" Ribbon has the "Type Exchange Password & Connect," (and the status bar says "NEED PASSWORD") if I click "Update Folder", it updates and the "Type Exchange Password & Connect" button goes away and the status bar changes to "CONNECTED TO: MICROSOFT EXCHANGE". And this process will work regardless of whether or not Outlook fires a PW dialog box until or unless I go too long without clicking "Update Folder" (such as over night).
But in the morning, if I get the PW dialog when I click the "Update Folder" button I just enter the PW one time and I'm back to being connected for the rest of the day (regardless of if or when I get the PW dialog boxes again or how many times I get them).
Actually, the only exception to this is on one of my Outlook accounts the "Type Exchange Password & Connect" doesn't go away until I click it.

But AGAIN, this is ALL being managed in Outlook. NOT ON YOUR SERVERS.

Which brings me to the prospect of a solution (or probably why there is no solution).
The solution is not and cannot be on your servers.
At least, not until or unless you configure your servers to send the messages our applications expect so they'll quit freaking out.
I wonder if there is or might be some reg keys we can edit or add which will enable our applications to stop freaking out or to disable the freak out mode.

I know MSFT's messaging has been that OL 2013 and I think OL 2016 are out of application support but we may still get security updates (I think).
I can't help but think a "security" update to add interaction with our registry to disable our applications from freaking out, or to enable them to manage it more appropriately might make this go away.

So yeah, this isn't my first rodeo with MSFT ( I used to work for MSFT years ago) so I know what I just wrote is an exercise in futility.
But I mention that because absent that happening, MSFT ought to be a bit more honest about what's really happening here.
It seems CLEAR to me that MSFT has changes it's server responses and these responses are trigging our applications to freak out without regard to our actual connection status. Further, MSFT is unwilling or unable to return to the old responses or add the old responses to the new responses or to provide an update to our applications to manage or disable the freak out episodes.

yes but my Hotmail account does not work with the new outlook app !

The issue is still random and have different patterns for different people. I am in Asia and Android EAS is nearly not usable and worse than when I was in the US. I moved some of my data to my Google account and things are incredibly smooth, even over roaming data. This move will backfire for Microsoft in the long run. They are doing all this to capture more users but then you have long-term customers like me that are so put off by this, it actually drive us away.

After several days of getting mail only via my Aondroid app, I tried Outlook 2013 again. I entered the password at the annoying prompt - the joy of all that pent-up junk mail getting through again was a joy to behold.

I did a test email and that worked too. Such randomness for a such a giant (dis)organisation.

Another example outside of Apple's client would be TbSync addin for thunderbird. They recently updated to support Modern Auth/OAuth using Exchange Active Sync. This is just a screenshot that I took when I tried it. TbSync :: Add-ons for Thunderbird