Relay problem remains

HI Guys,

There remains a relay problem.
Very odd.

Each time I want to send an e-mail through the server with the nserver itself as the sending smtp I get this error.

554 5.7.1 : Relay access denied

So using mail.servername.ext in my outlook does not allow me to send mail through the server. When I am an authenticated user I should be able to relay mail trhough the server, but I can't.

Must be something with the smtp settings, but I really don't know what...