smtp;550 5.7.1 Unable to relay for

I have setup a new server at a ISP (in internet) with Windows 2003 Server R2 64 bit and have installed Micosoft Exchanger Server 2007 sp1

After the setup I can send emails from to other servers and to my emial account, but when I reply to those messages, I get the following error:

Reporting-MTA: dns;
Received-From-MTA: dns;BAY143-W20
Arrival-Date: Sat, 23 May 2009 18:04:01 -0700

Final-Recipient: rfc822;
Action: failed
Status: 5.7.1
Diagnostic-Code: smtp;550 5.7.1 Unable to relay for

Can you please help? It have setup a SMTP connector already.
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

You likely have a problem with your recipient policies.  It sounds like is setup, but is not.  See
Sorry that was for 2003.  In 2007 recipient policies are called email address policies.
check if you have SMTP Service installed. if yes. disable it or uninstall it...
test the mail flow
HectorHugoGonzalezAuthor Commented:
I reinstalled the Exchange Server and then added a Sender a the organization level and it worked.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Windows Server 2003

From novice to tech pro — start learning today.