Error Sending Emails

I have MS Outlook MAC 2011 V 14.2.5.  I have 3 email accounts set up in Outlook - 1 Gmail and the other 2 Go Daddy.  I recently set up my accounts via Outlook.  The gmail account works fine, but the 2 Go Daddy accounts do not.  I am able to receive emails, but not send them.  Emails get stuck in my outbox and return a response "Authentication failed - user name and password or security settings incorrect".  I tried troubleshooting it through Go Daddy and I am told my settings are correct.  They are claiming everything is fine on both my and their end.  I also set up the accounts on my iPhone and all 3 work perfectly.  And, I tried deleting the accounts, shutting down/rebooting my computer and re-establishing the accounts.  Still the same issue. Can you help?