I have a client that wants to maintain control of his domain (fair enough) - he also wants to maintain control of his MX records (fair enough). He is with CrazyDomains and the current records kind of look like this:
NGINX can work as a load balancer and/or a proxy, which is the beauty of it all :-).
For the purpose of this example, let's say we have 3 clients we need to manage (i.e. host their sites).