I have a Go Daddy POP email account that stopped working with the upgrade to 10.10.4. Spend the better, part of a full day with AppleCare, tried everything we could think of, including trying to restore from Time Machine (which told me the backup was too large for my drive, which is an issue for another thread). I can still access the email from my iphone and ipad, but not the Mac, which makes me believe it's the OS and not Go Daddy. I've tried accessing from Mail, Outlook and Thunderbird, but it keeps rejecting my username and password (and yes, I checked the password, and can still login from my webmail). I'm honestly at a complete loss.