Proposal: Implement COI standard

I don’t know if you guys already intend to do this, but I found Delta Chat much similar to COI - Chat Over IMAP specification ( I think it could be worth to implement this emerging standard.

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Quote from your linked website :wink::

COI for Developers

COI is the only ecosystem that provides openness, a strong messaging basis AND overcomes the network effect.
With COI you don’t need to develop, host and maintain your own communication servers.
Thanks to Delta Chat Core, as a client developer you do not even need to deal with IMAP directly.


Where can I download clients? How can I test this?

  • OX - the initiator of the COI initiative - is working on its own COI compatible client. This one is MPL licensed and available at
  • We are cooperating with Delta.Chat for it to also use COI to provide more features, we are contributing to the C-Kernel of it.
  • We are cooperating withother client developers such as Thunderbird or Spike to get more clients use COI, and invite all ISV’s to join in. There are soooo many variants of Chat / Slack / Social Clients out there. Let’s put them on COI and make them interoperable and give users control over where all that data sits!
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Famous news. Nice! :sunglasses:

I think the whole COI thing was very badly communicated, not quite but as close as it gets to a PR-desaster. And I’m not just talking towards the COI side but also to the Delta Chat people. Neither the Delta Chat Twitter account nor the Delta Chat blog has anything regarding COI. I could’ve spent the whole day answering comments made on the internet, correcting wrong statements, answering questions etc…

@webratte, ouch… I just focused the specification document of COI and, after some search, I found Delta Chat, then I searched the source code and, even though it’s the same subject, the COI specifics are missing (headers, IMAP folders).
So, there is a roadmap of COI specification implementation? (Thanks @WinAuthFan)

Nice! I’ve tested OX Talk with DC and they speak the same language, even with the encryption business. I couldn’t test Spike app, though.

That’s because COI uses DC core :wink:


OX Server developing seems to go on.

Will you have a eye on features which will be possible with COI extentions?

I’m not sure what will come with thus extensions.
But I think there will be stuff like online state and so on.

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I think it would be a good idea to have a eye on the coi server extension.

There are a few nice additional features possible if this extension is aviable on the mail server.
E.g. typing notifications.
And still it stays backwards compatible to MUA’s if I understand this correctly with my bad english.

What do you think?

When they contribute back to our rust core as they said they will, to add these features, we can add them in the clients, but I wouldn’t focus too much on what they do with COI as long as it is all in an early state (the spec is still in draft state) and it isn’t deployed on many servers.
At the moment we have more concrete things that need to be done IMHO.


Yes of course.
I don’t say you have to do it immediately.

I only think it’s a good idea to keep a eye on this, because Chat over E-Mail can become a big thing.

Especially if there are typical IM features (typing notification, online state and other stuff) will be possible.

Isn’t it?

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