please note that all response codes are reported by the SMTP server, not the client.
The reported Response Code: 535 is specific to Yahoo, other server can have other error code for the same.
We don't have a document describing error codes, because it is server specific and we implement the client part.
I suggest you to handle exception, notify user that "Login failed." Then provide more detailed info which can contain exception message or server response and finally provide some hints (e.g. check your credentials, enable Less secure app, etc.)