Can't reinstate email account after clean install

Good news! I did read about disable, restart, enable after I posted - and was going to come back with that if necessary. atb, Martin

Okay guys, I got to the bottom of this... I made a mistake that fixed the problem!

Going into advanced options on setting up the email account, in the field that asks for email address, I gave my email address.

In the field that asks for Username I had been typing Andy Kay, but made the mistake of typing my email address again.
Then the account was up and running.

I have tried this with more accounts, and every time I put my user name in the field that asks for Username, it fails, and every time I put my email address in there it works.

Somebody at Microsoft needs shooting.