Zero metadata, group descriptions, native audio/video calls and more
Delta Chat and chatmail core teams have released version 2.48+, enhancing privacy with near-zero metadata transmission. The update includes full header protection, randomized dates, and encrypted group descriptions, while introducing native audio and video calling across platforms. These changes improve user privacy and functionality without relying on centralized infrastructure.
- ▪All meaningful message headers are now encrypted, with only minimal outer envelope data visible to transport servers.
- ▪The Date header is randomized within a 5-day window to prevent timestamp correlation attacks.
- ▪SecureJoin v3 encrypts initial chat setup messages and ensures backward and forward compatibility.
- ▪Native audio and video calls using WebRTC are now available on Android, iOS, and DeltaTouch with background support.
- ▪Group and broadcast channel descriptions are end-to-end encrypted and synchronized with membership changes.
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Story provenance
Attribution is not the same as permission. This drawer separates discovery metadata, excerpts, WeSearch-generated summaries, reuse status, and whether the publisher receives the visit. Nothing here claims a legal grant the publisher has not made.
Record
| Original publisher | Delta |
| Canonical URL | https://delta.chat/en/2026-03-31-zero |
| Publication time | Sat, 16 May 2026 12:25:35 +0000 |
| Retrieval time | 2026-05-16T12:40:18.509Z |
| Last seen | 2026-05-16T12:40:21.194Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | tTCnaWmJSi8v |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
Rights status (four layers)
WeSearch handling by dimension
| Indexing | May the item be indexed (stored, ranked, made findable)? | Allowed |
| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
Zero metadata, group descriptions, native audio/video calls and much more! March 31, 2026 by Delta Chat and chatmail core release teams 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 zero-metadata: No cleartext Auto-Submitted or threading headers. In addition to Subject, To, and group membership headers, we’re now also protecting Auto-Submitted, References, and In-Reply-To. This means that all meaningful header metadata now lives exclusively in the encrypted part of messages, implementing full Header Protection (RFC 9788). Transport servers only see a minimal so-called outer envelope. Randomized Date header.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at Delta.
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