Something like this:
https://www.ukpostbox.com/
https://www.myukmailbox.com/
Should be good business, as there is no such service in this country at the moment, as far as I know. And privacy standarts are high there.
But if you want to donate a small server (without Wordpress on it) to the TOR network, we would be happy to set it up and manage it to stay online
There could be some short term interest in that but I frankly doubt it compared with just plain oldfashioned throwaway emails. If one is sufficiently in need of privacy for that to be dangerous with metadata etc, shoudl one really be using email in the first place?
I used to run a service that would drop nodes on random QQ groups a few years back but it is getting ahrder and harder in some places to reliably help.
I think you misunderstand the meaning of such a service. Such an address can be used as a valid postal contact address in the inprint of a website. As a fully-fledged and working address, it can be used to protect the privacy of the website operator and his home address and comply with law at the same time.