Outlook 2010 After latest update = Disaster

This morning I downloaded a number of W10 updates onto my number 2 machine. This machine had my Hotmail and Outlook email accounts being managed via Microsoft Exchange. So, while I was messing around with this machine I thought that I would change them all to IMAP like my email accounts on my number 1 machine.
It has been a disaster !
I have gone round and round in circles with this problem for hours. I have done the disk cleanup and got rid of all of the unwanted system files etc (About 15 GB) And still the problem persists !

I keep getting the Nag Box indicated in red in the image below. This does not happen on my number 1 machine, no matter how often I enter the correct details, tick save password and save it keeps coming back again and again and again.
I have carefully duplicated the email setting exactly as they are on my number 1 machine, which works just fine.
Each machine is running W10 64 bit.
I am at a complete loss as to what to try next.

Do you think that it might be Mr Putin ?
Any ideas ?
FredM8

Thanks for the info Caledon.
I have two machines with same brand and chipset mobo, same os, pretty much the same progs. One woks with IMAP on all email accounts, and one is giving me these problems. I have no idea what could be causing the problem. Some other members have provided me with solutions some of which are more risky than others. I have yet to give them a try. I should not be so cowardly as that is the whole point of having a back up machine.

I will have to have a few stiff shots of Scotch, then get to work !

Hi there

@FredM8 -- think I'll join you with a glass (or two) of Scotch --Single Malt please !!!!

I have had problems with the wretched "Auto" configure stuff especially if you use your own domain for email

even when you try and set manually it asks for an email address and doesn't like it if the email address isn't the same as the account name who has access to the server (i.e the user id of the account holder on the server).

Best way is to use the Internet mail config applet in the control panel (for outlook 2010) or outlook 2016 applet for outlook 2016.

Check for outgoing mail that the "Use same settings as incoming mail" is unchecked - it's in the NEXT settings (can't show screenshot as I'm on Linux at the moment).

It should then all work fine -- no probs with outlook 2010 / IMAP servers etc with latest win 10 update -- BTW Outlook 2010 is still receiving updates from Ms so install those too.

Thumbs down -- mega thumbs down to those "auto config screens" -- especially when it gives you a choice of manual config and then insists you enter an email address and fails -- I might speak different English but doesn't manual mean manual -- not automated !!! -- Fortunately the applet in control panel works properly.

Cheers
jimbo