Apple Mail won't add a gmail address
When trying to add a gmail address to my MacBook Air I get this message:
Authorization Error
Error 400: invalid_request
You can't sign in to this app because it doesn't comply with Google's OAuth 2.0 policy for keeping apps secure.
You can let the app developer know that this app doesn't comply with one or more Google validation rules.
MacBook Air 13″, macOS 10.13