Using classic Outlook for Windows in business environments
I've yet to trawl through all the answers here but I've had the same problem for months on my WIndows 10 PC - password not accepted when trying to sync email - and the only solution was to use live.com in a browser or the God Awful 'New' Outlook
Today after seeing other peoples attempts to fix the issue I set up 'old' Outlook as the 'administrator' logon and it all worked .... all my email just synced without any issue .... looking at the default mail settings its using Exchange whereas my user account uses IMAP ....
So the solution would seem to be to go through the process of converting all the email in my IMAP account to using Exchange - and recreating my email account i nthe process - I could just create a new email account but this is my primary one
The funny thing is that my other hotmail account and my GMAIL which are both still IMAP are working fine