Apple Mail unable to verify account name or password

I have an early 2015 MacBook Air running latest OS Monterey 12.7.6. Until very recently had no problems then the message 'unable to verify account name or password' started to appear occasionally, but last couple of days it comes up every time I want to look at my mail.

Web mail and iPhone13 have no such problems so I know there is no problem with either user name or password.

From internet search it was suggested that I delete the account and add it back. Deleting was not a problem but when I tried to add it back when I submit the info in @Mail account, and click on sign in, it comes back with 'unable to verify account name or password'.

Any suggestions how to get my mail back on the MacBook Air.

Thanks

Andy