As I’ve discussed before, Proton doesn’t accept anonymous payments.
Hence, the best way to be anonymous with a Proton Mail account is with a free Proton Mail account, especially if you’re going to do politically risky stuff.
You should also keep in mind that since Proton knows all the usernames/addresses you have under the same account, they could be asked by authorities to provide them.
What I mean is, if you do activist work with your anonymous username bugs.bunny@pm.me, authorities could ask Proton to provide all the usernames / Proton addresses linked to the same account. And if one of them has your real name, jordan.smith@pm.me, you will be identified.
As far as I know, this has never happened. Authorities have never made such a request, but when I spoke to Proton’s legal team, they told me that if compelled to, they have to share your info. This means that they could.
I personally think that you shouldn’t have to pay or have multiple Proton accounts to protect your privacy.
Using Addy is smart because they accept anonymous payments. However, I don’t think it’s best to use Addy with a free Proton or Tuta account because they are very limited. If you have a lot of aliases, or even just a few where you receive a lot of emails, managing them with a free Proton or Tuta account is not practical. So maybe use Addy with a paid Tuta account, since both can be paid for anonymously.
I stopped using my Gmail three years ago, but I still haven’t made a full transition, because using aliases for email can be confusing for my family. Hence, it’s often easier for them to email me at my Gmail because they can’t remember which of my aliases is for what (lawyer, plumber, gardener, etc..) when I copy them in emails. I do not reply on Gmail, however.
It is my understanding that Addy does its best to collect the least data they can about you, hence why they have the option to pay anonymously via the Proxy Store. That being said, it is unclear to me if Addy can read your emails, even if it’s only within a brief nanosecond time window when it is received.
If you want to protect yourself, do not state your name or any personal info in the emails you send via your Addy aliases. Write to Addy’s support team anonymously. They will be very happy to answer your questions.
I have personally paid for Addy and Tuta anonymously, and my experience has been pretty good so far.