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After three intense months of work from more than a dozen contributors, #deltachat 2.48 releases are rolling. Maybe the most feature-packed releases ever?

- "zero metadata" messaging

- native Audio/Video calls on Android and iOS, as well as UbuntuTouch

- Group and Channel descriptions

- A new background audio player

- Revamped Download-on-Demand

and, last but not least, the long-awaited next-generation of messaging resiliency through "multi-path" routing ....

delta.chat/en/2026-03-31-zero


Delta Chat: Zero metadata, group descriptions, native audio/video calls and much more!

With the latest 2.48+ releases, a chat message reveals close to zero metadata to servers. For cryptographers and messenger enthusiasts, here are the key points on how we turned email very close to ...
delta.chat
#deltachat
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Götz Hoffart
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Götz Hoffart
• •
Ups, and what if i already enabled (and added) additional relays with 2.43 and I want to upgrade to 2.48 (where the rel-notes state "Ensure all your devices are upgraded to version 2.48 or later before enabling this feature.")
in reply to Götz Hoffart

Delta Chat
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Delta Chat
• •
@goetz this should work fine but it's better to upgrade still. Some details are better co-ordinated. But nothing bad or irreversible should happen if you use 2.43 and 2.48 side by side.
@Götz Hoffart
in reply to Götz Hoffart

Delta Chat
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Delta Chat
• •
@goetz You can "hide" all relays but one for now, this way all your contacts will send only to one relay and not trigger the bug in 2.43. This is actually done automatically during upgrade, by default all relays except the primary one are hidden right after upgrade, so you don't need to do anything.
@Götz Hoffart
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zivi
akkoma - Link to source
zivi
• •
havent you always been advertising “zero metadata”. now its zero-er? hmh
in reply to zivi

Delta Chat
mastodon - Link to source
Delta Chat
• •
@zaire we minimized metadata in prior steps, but only this release goes all the way. Maybe read the post for more context.
@zivi
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Kenny
sharkey - Link to source
Kenny
• •
It doesn't really go "all the way" though. Just because the email address is random, it doesn't make it unbreakable: it's still a unique and persistent identifier.
in reply to Kenny

zivi
akkoma - Link to source
zivi
• •
@kbruen that. the persistent email addresses have always been a concern of mine. they can be recorded, they can be tracked, what’s up with that
@Kenny
in reply to zivi

zivi
akkoma - Link to source
zivi
• •
@kbruen part of me feels like delta is so commited to staying “the email messenger” because of some sunk cost fallacy. dont get me wrong, it works, but theres so much extra working around flaws that wouldntve existed with a proper IM protocol that has to be done
@Kenny
in reply to zivi

Kenny
sharkey - Link to source
Kenny
• •
No. Using email as a backbone is one of the big selling points. Otherwise, there's dozens of apps out there. Using the email infrastructure brings advantages no other protocol can bring, such as censorship resistance.
That's not the issue here. For example, the blog post mentions multiple relays, but only one seems to be used for sending, which feels like that meme of a miner giving up right before reaching diamonds. If Delta Chat would send each message from a random relay, the problem would pretty much be solved. Alas, I have a love-hate relationship with Delta Chat, and I often find the choices of the devs puzzling.
in reply to Kenny

Delta Chat
mastodon - Link to source
Delta Chat
• •
@kbruen @zaire we are proceeding step-wise and aim to provide stable user experiences across versions. In the last section of the blog post delta.chat/en/2026-03-31-zero#… we already sketch a path forward that includes switching sending relays. But we need to move and change an implementation, and cant just work on the idea level alone.

Delta Chat: Zero metadata, group descriptions, native audio/video calls and much more!

With the latest 2.48+ releases, a chat message reveals close to zero metadata to servers. For cryptographers and messenger enthusiasts, here are the key points on how we turned email very close to ...
delta.chat
@Kenny @zivi
in reply to Delta Chat

dexternemrod
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dexternemrod
• •

@kbruen @zaire

I like the step-by-step approach.

As soon as address-randomization is reached, the next complaint is that only the same n-adresses are in the pool. So the next request is to let DC create its own addresses. Get me right: This would be an awesome feature, I just use this to demonstrate that this is the nature of iterative approaches and ongoing improvements.

@Kenny @zivi
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Séverin Lemaignan
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Séverin Lemaignan
• •
looks like an impressive release! Audio/video calls based on WebRTC 🤩 Congrats to the devs! imho, the last remaing hurdle for much greater reach for deltachat is contact discovery. Any plans/ideas about that?
in reply to Séverin Lemaignan

Delta Chat
mastodon - Link to source
Delta Chat
• •
@severin thanks! Unfortunately, it is not likely the apps will offer contact discovery themselves. It would bring #deltachat closer to being a social media app, and invite spam and abuse which we are not prepared to handle due to the decentralized nature of our efforts. We do not know, mediate or see any interactions between users, an providing central discovery would break that privacy property.
#deltachat @Séverin Lemaignan
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OnkelBobbyWhite
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OnkelBobbyWhite
• •
@severin When I recommend a Delta/Arcane, it's always one of the arguments why this is better than Whatsapp and Signal, and underlines the data protection is written big.
@Séverin Lemaignan
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Kevin_Runforrest
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Kevin_Runforrest
• •
a job well done, I was waiting for the support for audio and video calls, thank you very much to the developers.
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jaseg
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jaseg
• •
please correct me if i’m wrong. from your post it sound like what you call “zero metadata” isn’t metadata resistant in the sense that it doesn’t leak timing patterns to relay/mta or network adversaries, right?
in reply to jaseg

Delta Chat
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Delta Chat
• •
@jaseg yes, it's about message header metadata, and the fact that no cryptographic identities are visible on the transport layer, making it hard for hostile servers to track anything when users change relays. This blog post is not a security whitepaper, which we admittedly still need to update and produce.
@jaseg
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jaseg
mastodon - Link to source
jaseg
• •

thanks for the clarification. speaking from my network security background, the whole timing leakage is what i’d call metadata and what your “zero metadata” thing is protecting (AFAIU timestamps and cryptographic identities) in a cryptographic protocol i’d consider straight up data, not metadata.

thinking about an average user of a secure comms tool, i’d expect they would be surprised to learn that something that is “zero metadata” still leaks timing and through correlation identities.

in reply to jaseg

Delta Chat
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Delta Chat
• •
@jaseg in the very first sentence we try to clarify the scope, i.e. "With the latest 2.48+ releases, a chat message reveals close to zero metadata to servers." The key phrase here is "to servers", and we then detail all the data that was made invisible to the server.
If you want to discuss this further, it's maybe better done in a support forum post.
@jaseg
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jaseg
mastodon - Link to source
jaseg
• •
but it reveals timing, which everyone but you considers metadata, to servers
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Vint Prox
mastodon - Link to source
Vint Prox
• •
I swear I saw an incorrect diagram some hour ago, where Alice and Bob only use two of their relays, and while writing my own post I was like: "HUUUUH?". And now it's corrected.
This entry was edited (12 hours ago)
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d1
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d1
• •
congrats and thanks to everyone who worked on this 👏💖
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Blue Luma
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Blue Luma
• •
does DeltaChat use or intend to use a double ratchet encryption algorithm ?
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⁉️
mastodon - Link to source
⁉️
• •

Is telephony e2ee? You only mention peer-to-peer and no mention of e2ee.

Well done, you guys are really advancing at a rapid pace!

And please no contact-discovery!

in reply to ⁉️

Delta Chat
mastodon - Link to source
Delta Chat
• •
@chiefbongo yes, calls are end-to-end encrypted. Sorry for not making this more explicit. We also still have work to do to update docs and get everything stabilized 😅
@⁉️
in reply to ⁉️

Delta Chat
mastodon - Link to source
Delta Chat
• •
@chiefbongo and no worries, contact discovery is more or less a no-go area, even though it is lightly discussed sometimes, but certainly not via a centralized server, let alone one that we would run.
@⁉️
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