I use it for connecting my tiny SMTP ingress machine to my big SMTP backend machine and doing the ClamAV scanning over the VPN link (because it's now far too he

I use it for connecting my tiny SMTP ingress machine to my big SMTP backend machine and doing the ClamAV scanning over the VPN link (because it's now far too heavy for the tiny SMTP machine these days but the big machine has plenty of resources free.)