Exchange 2010, working through proxy on VPS?

Question

proxy

Good afternoon!
Please help me solve the problem.
There are home servers:
- as a gateway - pfsense (to which the Internet beeline comes, in addition to the wan port, l2tp is configured from above).
- as mail - exchange 2010.
Beeline provides a white ip (for example, 1.1.1.1) address, but ptr cannot make a record on my domain name. Therefore, I want to order a vps ( infobox.ru ), which has a white ip (for example, 2.2.2.2) and the ability to register a ptr record of my domain.
The goal is that all traffic that comes to 2.2.2.2 is redirected to 1.1.1.1 and already pfsense redirects to the mailer) and vice versa, so that mail goes through the vps server (2.2.2.2). Thus, what would the mail essentially work on receiving and sending through the vps server.