On Proton Mail

I’m not sure exactly why or when it happened, though seemingly the business model was started by the Snowden leaks, but there’s been a trend of more privacy-minded individuals and more tech-y users of switching and recommending Proton mail as the email provider you should be using. I believe that Proton does more harm than good due to privacy-washing email, making misleading claims about encryption, harming the decentralization of email, pushing users into their pseudo-walled gardens and at the same time offering less benefit to the user while charging more.

Below is an overview of the article with sections hyperlinked

Debunking marketing claims

“Ease of use”

One of the seemingly most apparent selling points of these services, a point which is often reinforced on their sites and guides, is that your messages are automatically encrypted in first-party communication (this term should already be icky in relation to email to anyone that wants to get away from Big Tech) - which is that when you are in an email conversation with another Proton user your emails will automatically be encrypted without you having to do any of the work so you can “let our software take care of these complex operations for you automatically” [bottom page of https://proton.me/support/how-to-use-pgp]. That is all nice and dandy but what about if you want to email someone who doesn’t use the same service as you, which looking at the data is most likely going to be the case as Gmail has 1.8 billion monthly active users globally, followed by iCloud, Outlook, Yahoo... all with hundreds of millions of users.

So we’ve established that you are most likely going to be sending emails to and receiving emails from people using another email provider, let’s see what the experience of that is like...

Proton uses an open standard for encryption, that standard being PGP which can even be used on Gmail with third party clients like Thunderbird or browser extensions such as Mailvelope. Proton allows you to use two methods to encrypt your emails when communicating with other email services; password-protected mail and PGP keys, both of which you can use from the official client, let’s look at the former first.

Using password-protected mail

Following the official guide the steps look something like this: https://proton.me/support/password-protected-emails

Sending:

  1. Choose to encrypt message with a password
  2. Enter a password
  3. Send

Viewing and replying as a non-Proton user:

  1. Open the email and click the link to view the message
  2. Enter the set password
  3. You can view the email and reply to it from their web interface

While this isn’t something you’ll likely want to use as PGP will be much more secure than a password there’s nothing wrong with Proton offering this and the implementation is likely the best you can do, either way let’s look at what you’ll actually want to use.

Using PGP

As before, based on the official guide the setup for this is pretty much the same as using any other email service provider (except Tuta).

If you are on the free tier: Using PGP encryption requires you to use a key stored on Proton’s servers as you cannot use third party PGP capable clients in combination with a PGP key you generated and stored outside of the Proton mail service. This also means that when migrating away you will have to inform everyone of a completely new key alongside your email address.

Proton also doesn’t seem to support using WKD (Web Key Directory) for users using custom domains.

Summary

Putting aside the marketing included in the guide posts that try to sell you on switching to Proton instead of doing the “complex” work of encrypting email yourself, the actual ability to do so exists albeit restricted outside of the paid subscription. That said, there is not much actual difference in the complexity of the setup of PGP on Proton’s website compared to using the universal aforementioned options, therefore I find the marketing claims about easing complexity to be unsubstantiated.

Privacy-washing

The PGP-sized elephant in the room

I don’t think an elephant that grows for every problem found with PGP would fit in a room but bear with me

PGP as it turns out should actually stand for Pretty Bad Privacy, I am not going to list all the issues with it as there are far more qualified people making posts that are far better at showing the issues so I will just insert a quick TL;DR, however please do read the linked posts, notably the sections about PGP use in email

-----BEGIN TL;DR-----

  1. PGP is a mess of methods and protocols
  2. It doesn’t support forward secrecy which makes it wholly unsuitable for private messaging
  3. When used in email it cannot encrypt metadata and it leaks metadata in general

-----END TL;DR-----

Some of the above reasons are even shared by Tuta as their reasoning for ditching PGP and offering a proprietary encryption method instead.

Proton

Just starting off, Proton uses the same “zero-access”/“zero-knowledge” marketing babble that many services like it do, as per Wikipedia;

unlike “end-to-end encryption”, the term “zero-knowledge” does not imply any specific threat model or security notion, and its use is commonly frowned-upon by the security community.

That should be a very real red flag for any seriously privacy conscious user looking at Proton’s offering, however there is more.

The encryption method

Proton relies wholly on PGP for their encryption, while this comes with the benefit of using open standards, for the reasons included in the above section and in the linked posts, I believe it is unsuitable to call Proton private.

As naturally follows I believe that the service purposefully misleads users. I believe this is further justified by them making misleading claims such as stating on the landing page

Proton Mail’s end-to-end encryption and zero-access encryption ensure only you can see your emails.

While when actually going through their other pages they state

when an email is sent from Gmail to Proton Mail, Proton’s servers can briefly read the message

and not just Proton can see your emails and not just briefly, if an email is sent to you from a Gmail address, Google can see the header and metadata of it even if it was PGP encrypted by the sender.

Unless you are using PGP encryption or you are emailing someone that uses Proton, your emails are not automatically end-to-end encrypted, and using end-to-end encryption is more work while being more limiting (password-protected emails have to be viewed on Proton Mail’s website) than doing so with standard email encryption that you can use among normal providers.

Proton also claims

all our code is open source

That statement only applies to client software; Proton’s server-side software is closed source.

Storing identifying details

Proton Mail provided Swiss authorities with payment data for defendtheatlantaforest@protonmail.com — the account linked to Stop Cop City protests in Atlanta. The FBI obtained this information through a Mutual Legal Assistance Treaty request on January 25, 2024, identifying the activist behind the anonymous account through their credit card identifier.

Contrary to what you might believe prior to reading this, it is possible to anonymize non-crypto payment data as demonstrated by Posteo, so why does an email provider who advertises itself as private not do so? And while not doing that, the only cryptocurrency Proton offers is fully traceable on the blockchain.

Proton also offers custom domains, which means they are required to store user information when a user uses a custom domain with their email service.

Gardens with high walls

Email is designed to be a decentralized protocol. That is why we have standards such as IMAP, standards which Proton throws out in lieu of using their proprietary bridge app that, as a cherry on top, is only available to paid accounts.

Instead of designing an interoperable standard that clients could be made with, they decided that the best way to make their email service not proprietary by users being limited to their clients was to make it proprietary by limiting users to their intermediate client.

On Andy Yen

Conclusion

So to put this straight; Proton is a service that sells itself as private while still suffering from the same issues that make email unsuitable for truly sensitive communication while also qualifying as a data processor which again, as demonstrated by Posteo doesn’t have to be the case for a private email provider. Proton paints itself as a service that promotes privacy and wants its users to depend on their expertise to stay private. Can they really achieve that while failing in so many fundamental ways? And can they REALLY achieve that when their CEO expresses opinions completely contradictory to their goal?

So what do I do?

A lot you can do actually:

  1. Don’t see email as private and don’t use it with the assumption and expectation that it is, email won the protocol war precisely because it is simple, encryption goes against that design and therefore will never be a first party citizen, if you want a private messaging system use Signal, if you want a decentralized private messaging system use Matrix
  2. Switch off of Proton

Switching

  • Infomaniak: A free Switzerland-based email provider that doesn’t advertise to you or sell your data while being fully interoperable with email standards.
  • Posteo: Posteo is a Germany-based email provider that, while they don’t offer custom domains, pride themselves on email privacy and running 100% on renewable energy, they anonymize payment methods, don’t qualify as a data processor and allow you to encrypt incoming mail with PGP automatically. Costs 1 EUR per month.
  • Mailbox: Another Germany-based provider that swaps the hardcore privacy of Posteo for custom domains while still respecting you as a user by not advertising to you or selling your data. Also runs on renewable energy but is more expensive than Posteo, at 4 EUR per month when using custom domains.
  • Purelymail: An extremely budget-friendly provider that lets you use as many custom domains and email addresses as you want while only costing $10 a year. It is, however, hosted on AWS.

There are also more options such as Fastmail and Zoho Mail you can check out yourself.

Please don’t switch to Tuta; much of the scrutiny in this post could also apply to them.

If you don’t need the extreme privacy of Posteo, I highly recommend using your own domain as that makes provider lock-in almost non-existent, as you can switch your provider within minutes. If you want to use a free option like Infomaniak, Porkbun (an amazing domain registrar) offers free email forwarding with their domains.