Web server and Mail server on 2 ispconfig

[adrenalinic]

Hi.
I have two vps using ispconfig. All works very great! Ispconfig is a beautiful work.

I would use one vps how webserver of domain example.com and use second vps how mail server of first vps hosting example.com.

1)How can configure first vps to send mail to second vps?
2)When add a mail account on ispconfig with web server of domain example.com, how can sincronyze mail account to second vps?
3)Or i have to configure mail account of domain on mail server??

Scusmy for bad form of question!

Thanks.
Josef