Introduced the SMTPAuthNoAuth mechanism in the auth.go file meant for instances where authentication is not required or supported. Adjusted tests in client_test.go to account for this new mechanism. Minor order modifications were also made to the list of supported SMTP AUTH types and respective tests for better consistency.
Introduced the SMTPAuthNoAuth mechanism in the auth.go file meant for instances where authentication is not required or supported. Adjusted tests in client_test.go to account for this new mechanism. Minor order modifications were also made to the list of supported SMTP AUTH types and respective tests for better consistency.
Closes #176