Not exactly a how-to, but i know no better place.
I ran into a couple of email providers which might be worth to look at:
https://www.safe-mail.net/cgi-bin/Safe- ... a-7e60576f
and a list at:
https://anonymous-proxy-servers.net/en/ ... vider.html
assuming one is not happy with riseup for this reason or another. tails has listed two other providers, i will add them asap.
I found another list of providers:
I got experience with none of them. I simply ran into the links.