Exhcnage 5.5 and 2003

[Lebanese_007]

OK, this is what happned

I have exchange 5.5 on win2k macine, i was trying to install exchange 2003 on a new machine (windows 2003 server) but it didn't let me becuase the Active Directory connectors are not upgraded on exchange 5.5, so i went and upgraded them from the exchange 2003 CD. then i went back to install it on windows 2003, it installed fine.

I moved my mailbox from exchange 5.5 to exchange 2003, i went fine, the problem is now that i CAN"T send e-mail to the outside world. eventhough i CAN get e-mail from the outside world!!! and from the people that are still in exchange 5.5. (They can send and recieve e-mail from inside and outside)

It gives me this error message

You do not have permission to send to this recipient. For assistance, contact your system administrator.

<mail.mydomain.COM #5.7.1 smtp;550 5.7.1 Unable to relay for "my outside e-mail">

PS: Both The exchange 5.5 and Exchange 2003 have 2 NIC cards, one for the outside world (Public address) and one in our LAN (Private Address).

Help Pleaseeeeeeeeee