So, I was trying to setup multiple Apache Virtual Hosts. Everything was O.K, LAMP worked fine except for one and big problem: Postfix.
I have two domains. And two PHP/MySQL applications running on each virtual host, with it's own domain. E.g: I have OpenCart in domain1.com and WordPress in domain2.com, but PostFix send all OpenCart and WordPress mail from domain1.com OR domain2.com.
There's a way to "fix" it?