Just set up new Mac Mail (from a Migration Assistant process) and the Mail setup works fine but the Apple Mail then changes my username from the email - strips off the @name.name and gives the message the password is wrong - this is the case for all email accounts except for the iCloud email. Deleted all email accounts and re-added. Set up again works correctly but then not able to get any additional mail due to 'incorrect password' when it's the username that Mac Mail is using that is wrong. I'm not able to edit the username. What has happened that Apple is being so restrictive on allowing me to set up my own Mail account? Why are they changing the username and not allowing me to fix it? Any help is appreciated.
