#128 O365Modern question

When I use Office365Modern authenication, what do I need to use in the SMTPClient?
My own password? Or blank?
It is complaining about authentication failed: invalid user or pawwrod

var clt = new SmtpClient()
            {
                Host = "localhost",
                Port = 1025,
                Username = JvvEmail,
                Password = MyPassword
            };
            clt.Send(TestMessage(JvvEmail, JvvEmail, "test message using DavMail"));