How does delta deal with new chats, fallback and other standard email client stuff? Does it allow mixing encrypted and unencrypted messages? What happens if I use an alternative mail client, will I still be able to read email from people after the project dies and the clients stop working?

I don't think people will appreciate it when I suddenly start using email as a standard communications method, but it's worth a shot. The client looks like a copy of Telegram (a good thing, in my opinion) and everyone already has email, so I'm willing to give it a shot I guess. I'm currently on the Matrix camp but it's not like that's a protocol many non techs use in the real world.

I'm just wary of using email for this because of all of the previous failures to secure email, like PGP, S/MIME and variations thereof.

> Does it allow mixing encrypted and unencrypted messages? What happens if I use an alternative mail client, will I still be able to read email from people after the project dies and the clients stop working?

Yes. It uses the AutoCrypt standard, which exists independent of delta chat and has standalone software, + plugins for various email clients. I use a plugin for mutt so I can read my delta chat messages without the official client. You can issue new key pairs or turn off e2e as you like.

> I don't think people will appreciate it when I suddenly start using email as a standard communications method, but it's worth a shot

Fair, though perhaps technically simpler than getting others to download Yet Another Chat App™.

> ...previous failures to secure email, like PGP, S/MIME and variations thereof.

Did PGP and S/MIME fail? Services like ProtonMail use that tech to great effect. IMO it never hit the main stream because mainstream mail providers, etc want to read your email. There's some argument about usability but after using ProtonMail I don't buy those arguments.

> Did PGP and S/MIME fail? Services like ProtonMail use that tech to great effect. IMO it never hit the main stream because mainstream mail providers, etc want to read your email. There's some argument about usability but after using ProtonMail I don't buy those arguments.

In my personal experience, I've never seen anyone use PGP extensively for more than a month or so. The lack of PGP in most common mobile mail clients certainly doesn't help; switching email apps is annoying.

I don't think companies reading your email is the main incentive for companies to not implement PGP. It's perfectly possible to do PGP server side for free mail accounts like Gmail or Outlook, with proper PGP support in Outlook, Thunderbird, Apple Mail, etc.

PGP is complex, especially for people who don't know cryptography, and the lack of cloud sync of private keys and central account management makes it much harder to use than modern chat applications even for non-novice users.

I've never used ProtonMail and I don't know anyone who does, so my experience may not be representative. Then again, the fact I don't know anyone who uses ProtonMail might also indicate that PGP still hasn't gained that much market share.

It seems to use E2E encryption with some trust-on-first-use protocol called Autocrypt:

https://delta.chat/en/help#encryption

I really like the idea of delta chat, except that I cannot bring myself to allow it access to my full imap mailbox. And most providers do not offer a way to scope access to only selected folders.

You can use a separate mailbox just for delta chat

Sure. But that throws away the advantage of already having an identity.