Avoid address rewrite for my zimbra's domains.

[sevy72]

Hi all,
i'm new to zimbra , i 'm configuring this worderful system, but i encountered a problem. This is my situation:

I have two offices , two servers and two "fake" domains , one server for one office, every zimbra server have its own ldap ( one in slave mode), MTA, Store, Log..ecc..e.cc.. The servers are connected by vpn network

On master office i have master zimbra ldap server, that have two domains : company1.loc and company2.loc ( remember are "fake" or "private" domains, i have my own DNS)

I have setup the "smtp_generic_maps" on postfix main.cf to translate company1.loc to real-company1.com and company2.loc to real-company2.com on outgoing emails.

The problem is that if a user@company1.loc send an email to user1@company2.loc , postfix does the translation!

I want that postfix translate only email directed to "external" internet domains, not to my "internal & fake" local network domains.

How i can do this? I'm going crazy ;-)
Thakyou in advance!