problem with exchange 2003

Hi

i have problem with exchange 2003

when i try send mail to spicific domain i got error:

Your message did not reach some or all of the intended recipients.

      Subject:   

      Sent: 20/12/2012 10:04 AM

The following recipient(s) cannot be reached:

     xxxxxxxxxx on 20/12/2012 10:04 AM

            There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.

            <xxxxxxxxxx #5.5.0 smtp;550 Recipient address rejected: Relaying denied>

i check few stuff:

1. check in google and they recommend to in relay restricitions under tab relay and 

check "allow all computers which succesfulyy authenticate to relay, regardless of the list above". i did it

2.check with my isp provider and they say that in my exchange 2003 problem 

3. when i try send mail to this domain from telnet , its working

what can to be a problem in exchange, 

i cant send mail to all mailbox on this domain (they can send to me)