Can't log into Road Runner Mail
After upgrade to El Capitan, when opening Mac Mail I get the Notification "Can't connect to the account 'Road Runner - XXXX'. Enter the password for user 'XXXX'." So I can't log into Road Runner using Apple Mail. My other Mac Mail gmail account works fine. When I click on Continue, the System Preferences window appears and asks for the password, but it isn't accepted. Message says "Unable to verify account name or password." Nay ideas on how to resolve this?
iMac, OS X El Capitan (10.11.1)