From your description it sounds like the feature you might be thinking of as walled-garden-ing is end-to-end encrypted (e2ee) emails, which they call “confidential”. The idea is that you can encrypt a message and send it to someone. The message they receive is actually just a link to a publicly-accessible page that Tuta hosts. You give the other person a password that they can enter on that page to read the email you sent and respond to it. If your recipient is also using Tuta, though, when you send an encrypted email it just shows up in their inbox like a regular email.
This is the standard way to handle secure emails, and it’s actually a limitation of the email protocol. The way you would send an encrypted message to someone on another email server is to encrypt the email with your recipient’s public key. Then the message goes to their email inbox like a regular email and they can use their private key to decrypt it (which is what Tuta does if you’re sending an encrypted email to another Tuta user–they already have the recipient’s public key). Email servers don’t have a standard way to send each other public keys for accounts, so if you want to encrypt an email you either have to get the recipient’s public key yourself and tell your email software to encrypt the message with it, or have your provider send a password protected link.
I actually just switched to Tuta. You can still get and receive normal unencrypted emails. The encryption is optional and not enabled by default. I don’t have strong feelings one way or the other yet on the service as a whole. They just added the ability to import emails exported from another service, which is usually something email providers do pretty early on. Currently it’s only available at the $8/month tier, but it’s speculated that they’ll roll it out to the $3/month tier once it’s stable. That’ll be a non-starter for a lot of people. The client UI is simple but functional. It was easy to set up my domain so I don’t have to go into each account and update my email address. Yeah, no complaints so far, but also nothing that blows me away. There’s a free tier if you wanted to just poke around.
That all makes sense. You described yourself as a non-techie, so I misunderstood and thought you had assumed that all emails had to go through their portal.
You’re correct that Tuta doesn’t support PGP or S/MIME, which I didn’t realize. I assumed that any email service that has the word “privacy” on their website would support both. I don’t use personal email for sensitive communications, so I’m not in the habit of using PGP or S/MIME, but still… come on.
Their reasoning seems a bit silly. They say they don’t support PGP because it doesn’t encrypt the subject line, and it doesn’t support post-quantum algorithms or forward secrecy. That’s, at most, a warning line in the GUI, not something you just don’t implement.
They say they don’t implement S/MIME because of EFail, a seven year old vulnerability. They can’t confirm that all external services have a mitigation in place for it. But again, just put a warning on the UI. Could even build a list of external providers that mitigate it and only show the warning if the user is sending to a system not on the list.
There are a lot of places on Tuta’s website where they say they’re working on features but don’t specify a timeline, and a quick scan through their github issues finds some conversations where they indicate developer resources are low and they’re focused on post quantum encryption first, but they said that for years. Seems they didn’t implement basic features because they wanted the one big QC feature. They stated in 2020 that they intend to support PGP and Autocrypt, but they removed those from their roadmap. They’re not a current priority.
“Once our PQ-encryption is in place we can consider how to best interop with others keeping benefits of perfect secrecy and post-quantum encryption.” So it looks like they’re letting Perfect be the enemy of Good.
Yep, I can totally see the walled garden aspect. If you want PGP, Autocrypt, or S/MIME, find another provider until Tuta gets around to implementing them. A lot of their communications read as though they don’t have enough development staff to chew what they’re biting off.
ETA: I don’t see any scaling option in their desktop app, but you can launch it with GDK_DPI_SCALE=1.25 (or some other number) to embiggen it.