So, although Microsoft is going to feign deafness, my two cents.
I will simplify:
Microsoft does NOT want us to use POP accounts anymore, so the NEW Outlook does not allow for POP accounts. For those of us who manage our own email stores, this means taking our (often) large pst files, saving them, and restarting with IMAP, where, in order to store those large file stores in the cloud we will be forced to pay Microsoft for more storage, something we have not had to do. This, even though we PURCHASED premium permanent versions of Office, ie 2013 or 2016.
It gets better:
Outlook 2013 and 2016 is NO LONGER SUPPORTED. Of course it isn't. Convenient for MS. It means they can distance themselves from the reality of their changes, and hide behind what we MUST do, because they say so. This instead of actually supporting their long-term customers.
OK, there's more:
Outlook 2013 and 2016 no longer support our Hotmail accounts. We now get the well-documented problem with Hotmail as thousands of people are reporting. There are several authentication loops that are DESIGNED not to work together. And, once again, MS has apparently NO INTENTION of fixing this, judging by the well-documented remarks on this thread alone.
So, here is where I sit:
--My two POP accounts work fine on Outlook 2013 or 2016
--They don't work on the NEW Outlook (foist upon me against my will, slid into an irrevocable update by MS)
--My several hotmail accounts don't work in Outlook 2013 or 2016
--They DO work (surprise, surprise) in the NEW Outlook
-- I CANNOT remove the main Outlook account from Office 2013 or 2016, because, you guessed it, my hotmail account is my MS account, and you can't remove or re-assign the MS account.
--None of the FIXES in this thread work. I have tried all that I am aware of
--MS doesn't just not help through ignorance or being too busy; MS doesn't help because they point out Office 2013 and 2016 are NO LONGER SUPPORTED, However, if I had been allowed to scrutinize the updates thrust upon me, I could have prevented the authentication change so I could preserve my email accounts, which are completely none of MS's business. In fact, accounts I have had for longer than many MS employees have been alive.
--So now I manage my POP accounts with Outlook 2013/2106, have to wait EVERY time until I can silence the popups for the Hotmail accounts I am prevented from removing, and manage my hotmail accounts with the NEW Outlook, where I cannot put my other email accounts, because they refuse POP
Now, in the absence of meaningful help from Microsoft, all I can do is wait for the inevitable class action lawsuit (I got paid in the last one for similar unyielding practices from MS), unless someone decides to pay attention to the many people having this problem and allow their service to be restored.
If this message is removed for any reason, I will add that to my justification to being enjoined on the inevitable class action.
Your turn, Microsoft. From your side, an easy fix. But one where you need to look after OUR interests, not try to get us to endorse YOURS. What's it going to be?