Exchange with Zimbra split domain "User unknown"

[Salva_savia]

Hi
I have configured my mail scenario using this page.
Split domain with Exchange 2003 as Primary - Zimbra :: Wiki
I have an exchange 2003 as primary mail server, and a zimbra as secondary mail server.
All is configured ok, but when I send an email from google to an account in my domain i receive "5.1.1 User unknown", its true, the user doesn't exists in my exchange but exchange must relay this email to my zimbra server where exists that user....
I don't know what to see...
Thanks