Q: Cannot send MacMail. All connections to server okay. Error message Authentication Required. Any ideas?

Good Afternoon CornishClogs,

If you are receiving an "authentication required" error message when trying to send email messages in the Mail app, you may need to re-enter or reset your password.  Take a look at the troubleshooting steps for outgoing mail in the articles below.

Mail (Mavericks): Verify your outgoing mail server
https://support.apple.com/kb/PH14926?locale=en_US&viewlocale=en_US

Mail (Mavericks): If you can’t send messages
https://support.apple.com/kb/PH14933?locale=en_US

If you can’t send or receive email on your Mac - Apple Support
https://support.apple.com/en-us/HT204075

Regards,

Judy