Thanks a lot for DeltaChat. Coming from Signal, Element and SimpleX DeltaChat is exactly what we have been looking for for business (and private) team communication.
I have a few questions. Please tell me if I should rather split them into multiple posts.
We can use a classic email server with almost “unlimited” storage space. What is more future proof/recommended: Using our classic email server or a public chatmail server which “only” provides 400MB of storage? We need to share image files in original quality regularly. Currenty, we have no option to run a chatmail server of our own.
Is it possible to hide email addresses from invitation links? We would like to share contact links publicly. Or would you just reset the link/QR code from time to time which is currently possible in the mobile apps?
If I change my invitation link, will also chat room invitation links become invalid? This is not made clear in the mobile app versions.
no, how would you even do that technically? email network needs to know where to send a message to. you may use a link shortener to obfuscate it a bit.
make a different account/profile for public communication or depending on the use case if you have a customer support line for example you may want to use a team response bot or a helpline system like chatwoot:
In some use cases you may also get away with just using an email alias, but emails wouldn’t be encrypted because the alias has no key.
no, you need to do that specifically on the chat room invite links you want to deactivate.
Scan the link yourself to get the dialog asking if you want to deactivate (or reactivate) it.
chatmail is just a normal dovecot + postfix setup with a few modifications:
only allow encrypted outgoing mail
public open account creation with “first login is account registration”
dovecot mod that removes a delay in email delivery speed
reliable push notifications over google and apple push systems (necessary because many mobile device operating systems don’t allow Delta chat to stay connected to the email server in the background)
emails are directly deleted on the server after they have reached the device (unless you have multiple devices on one account)
For large file sharing I’d use a file server like next cloud or a file transfer service like https://wormhole.app, because deltachat does not yet a way to transfer large files. (in this forum there are multiple discussions on how large file transfer could be implemented)
Hi and thank you very much for your answers. That’s all clear and comprehensible.
I hope to understand these details correctly:
emails are directly deleted on the server after they have reached the device
This answers my main question. So, this also means that you probably should use a classic email server if you want to keep a chat archive across devices and plan to add devices later.
(unless you have multiple devices on one account)
But this probably does not mean that messages won’t be deleted (apart from unconditional message deletion after at most 20 days) if you don’t read them on all your devices (because DeltaChat cannot know how many different devices I use).
When adding a second device it copies all the messages that are already in your Delta Chat, you dont need to keep the messages in the server for that, Delta Chat works offline-first, all is downloaded and stored locally then the server doesn’t need to have all stored, it will all be stored locally in all your devices
Your classic email server will be probably a bit slower and not have push notifications, but otherwise it is probably the best to use it since you already have it and it will be more flexible, allowing unencrypted messages
Thanks a lot for your replies. I’m completely sold now.
Perfect. That’s good and important to know. I was confused seeing a storage limit of 400MB in the Delta Chat iOS app using a public chatmail server.
You are right. I see the advantages of both options now. But I guess for a company chat system an own classic email server probably is the way to go, indeed.