if the email is sending, you do not need authentication.
you say:
![](http://www.webassist.com/images/forums/q.gif)
![](http://www.webassist.com/images/forums/q2.gif)
where do you see this error? in the browser? is that the exact text of the error message, or are you paraphrasing? that does not sound like a familiar error to me.
can you send a screen shot showing the error.