Public Group Chats possible?

I am taking a look at Delta Chat. I haven’t used it extensively yet. Before I dip my toe further and try it out extensively, I would like to know a few things around the possibility of using Delta for group chats:

  1. Are public group chats possible with Delta chat? If so, what are the group chat capabilities available:
    a. can I set up a public group chat name that’s uniform for every member in the group chat?
    b. can I set up a group chat profile picture?
    c. do we have basic moderation tools for the such chats, like, removing a new spam message, or kicking trolls/spammers out of the group chat

  2. How performant is the autocrypt pgp implementation for public group chats? Currently, Matrix protocol sucks much for end-to-end-encrypted public group chats, because it takes around 10-30 seconds of wait for the element client to encrypt the message to a 300-odd people in the group chat. How’s this for Delta?

I’m not aware of them being possible at this time, though I’d also be interested in them for use as a backup / alternative to Slack or MS teams if an outage takes out the primary collaboration setup. Since the work context is on email servers, we would intentionally choose to let people come and go and see history and not encrypt the messages with autocrypt in some cases, that way we could bulk backup public chat rooms via standard email files, etc.

DeltaChat is not made for for the multiple 100 people groups, but you can make mailing lists, at the moment only unencrypted mailing lists are possible to my knowledge, but schleuder recently added some auto crypt support (Key auto import from email (!426) · Merge requests · schleuder / schleuder · GitLab), so will probably be possible in the future. mailing lists also have the advantage of making anonymous groups possible by hiding the email addresses.

That being said delta chat stores all messages locally, IMAP is more used like a transport protocol, delta chat itself is offline-first, if you have huge busy groups you either:

  • need storage space for all the messages on your device,
  • or disable automatic downloading of large messages such as images
  • or enable disappearing messages in the chat for everyone or autodeletion from your device after X time

Though normally messages are small, like you can get tons of text messages before it becomes an issue, but depends on your available storage space.

Normal groups can be public, you can share the invitation qr code or link, only limitation is that your device needs to be online for the other person to join, but there are bots that can do this for you. (current favourite GitHub - deltachat-bot/invitebot: Delta Chat bot that allows to generate invitation QRs and links for your private groups; older bot with web interface: Public Groups - a bot to let others join your channel)

a. yes
b. yes
c. moderation tools

  • cleaning chat: no once people received the messages you can not remove them from their device
  • kicking people is possible with removing members, but there are ways to get work around that and come back to the group, so you only really can get real moderation with mailing lists (those are proxies and you decide who can send or join them.)
  • authoritative groups with admins are really hard in decentralised settings also see New feature: Group Types
  1. performance:
  • for delta chat the biggest group I’m currently in is 76 members. This group still works nicely, limits depend on header size limits and recipient / rate limits of the involved email providers.
  • in group chats the messages are encrypted symmetrically and then the symmetric key is encrypted for every person ans sent in an email header.

In the future this might change, I myself are not really knowledgeable in OpenPGP, but there are interesting developments and innovation happening from what I heard.

That’s a shame. I think that usecase (if supported) would increase delta chat’s adoption. It’s current vision is focused but narrow.

What does that mean? I have never used mailing lists (born too late for them). Are they something like “Channels” one subscribes to on Telegram-like chat apps?

Having e2ee “Channels” (I guess mailing lists, in your lingo?) sounds cool.

An unpleasant limitation.

I think that’s not a huge turn-off, since we have something similar “ban evasion” tactics on tg/discord/et al. The biggest turn-off for me seems like in large group chats, in their current form, any newcomer to the chat can kick any other member. That is one of the biggest roadblocks towards adopting Delta Chat for xmpp/matrix/tg alternative, imo.

mailing lists can be used kinda like telegram channels or telegram super chats/groups, basically you have a server that forwards the emails to subscribers and you can have admins for that server that can kick/ban/approve people. Basically it is a centralised authority which makes having admins way easier than with a decentralised/federated system like delta chat.

you can not really get rid of that limitation unless you add a server.

I agree it would be nice to have sth like that, but unless you use some mailing list such a group could only have one admin, given that each group member would check if the action was permitted by the admins, adding and removing admins could be unstable if emails get lost or delayed between providers, like you would have inconsistent state between different group members. maybe there are algorithms to solve it, but I think the mailing list route is much easier.