Outlook 2016 doesn't accept password or app password

"Get a new office version" would not be such a big deal if

1. new version didn't have same issue as older ones

I have M365 Outlook installed at the moment and everything works fine. Which issue are you saying exists on this version?

Thanks a lot for checking.

Now we need an official answer from microsoft for this as it makes no sense to push the third party app developer to change to modern auth when it will not work for consumer accounts.

And in addition to this: If it is not possible to connect to outlook.com consumer account with modern auth and a protocol that supports Calendar, Contacts and E-Mail synching, I do not need a microsoft outlook.com account anymore, since this is the only thing I do with the account.

A bit more luck for me. I could not connect to eas.outlook.com or m.outlook.com on my main phone in the last few days. I have tried many many times on my phone + 2 other Android devices, but no luck. These have stock Android 12, 13 and 14 environments. Every time I add it as Exchange account type at the OS's account screen, I would get "...cannot connect to server...contact your IT..." error. I repeatedly submit add and it would keep getting the error message.

About an hour ago, I was suddenly able to add the account back with no other changes, on all 3 devices after 2.5 days of attempts. Sync of emails/contacts/calendar all worked. Now, here comes the interesting part. In Android account entry for the added Exchange account, there is a "Server settings" section near the bottom. Under "Incoming settings" selection, your account related settings are all listed. At the very bottom, there is OS option called "Switch to modern auth". This appears to be conversion option without user retype the credentials. Once I click this, a browser session is launched, similar to normal OAuth login screen. I would error out at this point after multiple attempts. If I abandon this, the account remains working.

I then retry the same process with my work account. Initially manually adding it, so it would be Basic Auth, then I use the same "Switch to modern auth" and is able to successfully convert to Modern Auth. This show this conversion function works. This goes further to strengthen the argument that EAS with OAuth may not be supported or is not currently working correctly for consumer email accounts such as Hotmail.

From Not the community crew:

I only found it once.
I used to add the ExcludeExplicitO365Endpoint =1 once, and the setting remain unchanged for several months around Nov 2023 -Feb 2024.
I just found it in the outlook account window was as imap once time just after adding the account via the Mail in the control panel. It happend around Jan or Feb 2024.
And I just delete it and delete the ExcludeExplicitO365Endpoint and recreate the accounts via the classic outlook.

Most of the time, I only use the mail in the control panel to create profile only.
Most of the time I add the accounts via the classic outlook.

The accounts are listed as Microsoft Exchange in the account window in the outlook in my usually creating account process, and should be via MAPI over http.
I don't know if the way use the EWS or not, but I always set the "Turn on shared calendar improvements" which should be rest API or somthing.And the It will be showing checking the contacts folder in the tray while opening the outlook.

I did not know how the autodiscovered imap outlook account behaves since it should only sync mail, and I delete it right after found it is imap.

I just wonder that if the "ExcludeExplicitO365Endpoint"=1 and the IMAP account autodiscovered mean that there are servers are not as office365endpoint but still offer imap autodicover via the personal outlook.com address around Jan or Feb 2024.

And I only add one account each time, it should be my oldest account created in the homail period, but lost the hotmail.com suffix during the live.com to outlook.com period.
I did not know how my live.com period account and outlook.com period account behave. (3 of them are all have only outlook.com suffix now.)

Very interesting... So with your Outlook 2021, and without the ExcludeExplicitO365Endpoint regkey, you were able to use auto-discovery to add your Hotmail accounts as IMAP, right? Are your email/contact/calendar sync or just email sync?