Replying to @hondanhon and @blaine, @Fastmail, @1Password
That part is a problem, as it is with all the other relay offers. But I don't think that anyone has figured a way around that so long as emails are used. It's that or being tracked across sites (or running your own email).
I would expect that it would be possible to keep the cheapest Fastmail running and just forward.
Ultimately, we need a more effective standard to destroy identity online. Until we get that, I'm afraid this is as good as it gets, though.