You’re right I should clarify!
The situation is the following:
I would like to use two VPS, with two different IP address and two FQDN.
On the first VPS, IP 126.96.36.199 the server web with DNS domain name example.com
On the second VPS IP 188.8.131.52 the server mail with DNS MX domain mail.example.com and DNS SMTP entry smtp.example.com.
And so goes on for each new domain which I will add in the future, example.net, example.org, etc, etc…
I don’t know for now, this system is virgin and I will have to build it from scratch.
The only thing is that I would like to keep the web services separate from the mail ones, and here is the need to keep two servers. So I need your suggest for the simpler situation.