Hi, to get the exact error configure Outlook Express or MS outlook with the same SMTP and check whether you can send mail if not you would get the error message like relaying denied etc. If you get any message check with exchange admin or post the error here.

Have you checked the Relay Restrictions in your Exchange Server?

Hi,

You can use "Blat", for configuring of email notifications.

It is easier to use and is free to download, also networker functions quite well alongwith it too.

For this particular error he would get the same with blat... I believe Sergio was on right track with his suggestion.

Hello,
try to add option -f (from) to the command line. And make sure that you put your domain after the @. Like your.address@yourmaildomain.com.
Exchange can be configured to only relay smtpmails from own domain...

Kind regards