Problem sending email with outlook 2010

Hi,

I've recently installed MS Office Professional Plus Beta 2010 on my machine. Earlier I'd office 2007 installed.
In our local environment we have Exchange 2007 installed. With Outlook 2007 I was able to send and receive all emails, but after installation of outlook 2010, i'm unable to send email to outside domain email address. At the same time i can send email to email addresses that are part of our local domain.

I'm getting following error:

            Server error: '550 5.7.1 Unable to relay'

Any hint?


Apart from this I'm getting same issue when i use exchange 2010 account with outlook 2010.

Thanks

Sandip