How is that lukewarm? Sounds like first class support if they have a dedicated onion address and not just let you connect to the regular clearnet. Or is that address only in that old blog post and not mentioned in places you'd usually look? It's a bit unclear to me.

It's lukewarm because what less could you do besides not support Tor?

Tor is mentioned on their homepage in the bottom menu under "Onion Site". However, this menu link redirects to their Tor placeholder page, rather than directly to the Tor service: https://protonmail.com/tor

There's one blog post from 2017 that still promotes their old v2 onion address: https://protonmail.com/blog/tor-encrypted-email/

Protonmail's Tor service is located at: https://protonmailrmez3lotccipshtkleegetolb73fuirgj7r4o4vfu7...

> It's lukewarm because what less could you do besides not support Tor?

Alright then, what more do you want them to do? Spend millions in court fighting every warrant issued for their users and go bankrupt defending criminal activity?

Aren't a big part of Tor entry/exit nodes considered to be monitored or even operated by the authorities?

The authorities don't need to run exit nodes, they just pwn enough routers, have enough interception devices or buy enough netflow data that they can trace data flowing through the Tor work back to its original location.

Sure, but if that becomes a problem for you depends on

1. whether or not your request stays within the tor network or not (if you use the .onion address, no need for an exit node)

2. given both entry and exit nodes can be literally all over the world: your threat opposition level. I doubt the NSA will be happy to help French authorities trying to catch a teenager who blockaded a government parking garage).

What does using Tor have to do with trusting math?

"What makes Tor different from the usual thesaurus-full of government projects is that Tor is essentially a very elaborate math trick, using layers of math puzzles to create a network-within-the-network. That math is being implemented in front of a global audience of millions of sophisticated watchers. It is likely the most examined codebase in the world. It has been subjected to multiple public audits. The math, well known and widely standardized, will work for everyone, or it will not, whoever pays the bills."

from https://pando.com/2014/12/09/clearing-the-air-around-tor/

"Trusting mathematics" would be a much more accurate claim if we were talking about mix networks, such as Loopix (https://arxiv.org/abs/1703.00536). But Tor is vulnerable to confirmation attacks to varying degrees, (depending on whether you are accessing clearnet or not, of course) which is very much worth noting in the context of a global passive adversary.