This is what I'm looking for.
To configure linux server (preferably centos 5) running interspire/postfix as smarthost to rotate smtp/ip/domains and relay mail through external smtp servers (postfix).
I also need a step-by-step on how to do it on my own.
It is essential to leave no footprints and rewrite headers with smpt ip and hostname.
I'm sorry if it's not very clear. If you have any questions or suggestions please do not hesitate to contact me.