June 2026 (2026-06) monthly summary for chatmail/core: Onboarding reliability improvements, cryptography observability enhancements, and onboarding governance enhancements. Key features delivered include fixes to QR-based onboarding channel titles, expanded cryptography statistics instrumentation, and onboarding defaults for relay candidates with an admin-approval workflow. These changes drive tangible business value by improving onboarding consistency, security visibility, and governance controls, supported by regression and unit tests.

Month: 2026-05 highlights: delivered two high-impact improvements to chatmail/core that strengthen reliability, data integrity, and developer efficiency. 1) Key features delivered - Documentation update to testing infrastructure: Updated README to use ci-chatmail for testing instead of nine.testrun.org, signaling a shift to a more reliable testing domain and reducing CI fragility. - Commit: 4bdc3c29edf26004b6c36c733030cfb3f33cb2d1 (docs: Update README.md: Use ci-chatmail instead of nine (#8238)) 2) Major bugs fixed - Chatmail Message Deletion Reliability Fix: Corrected server-side deletion logic, removed obsolete delete_server_after configuration, and ensured pre- and post-messages are properly marked for deletion in single-device profiles. Broadly improves consistency of message lifecycle and prevents stale data from remaining on the server. - Commit: 961cacd795c03bf963a8a1ba154a85668896804b (fix: Correctly delete unneeded messages on the server; Remove "Delete Messages from Server" (delete_server_after) config option (#8240)) - Notes in commit describe targeted SQL logic changes and expanded test coverage for edge cases (pre/post message handling, bcc_self behavior, and multi-account scenarios). 3) Overall impact and accomplishments - Improved reliability of testing and CI workflows by standardizing on ci-chatmail, leading to faster feedback and fewer flaky tests. - Strengthened message lifecycle integrity by aligning deletion behavior with actual user expectations across single-device profiles, reducing data remnants and potential privacy concerns. - Reduced maintenance overhead by removing a deprecated config flag (delete_server_after). 4) Technologies/skills demonstrated - Testing and CI strategy: documented and standardized on ci-chatmail; contributed to test thinking around end-to-end deletion flows. - Backend data lifecycle: SQL-level adjustments in delete_expired_imap_messages to include pre_rfc724_mid alongside rfc724_mid; handling multi-part messages to ensure deletions propagate correctly. - Code quality and testing: extensive in-code documentation, test coverage alignment, and clear commit messages that map to PR issues (#8195, #8217, #8240). Business value: The month’s work reduces risk of orphaned messages, enhances data privacy controls, and accelerates developer feedback loops, supporting more reliable customer experiences and quicker iteration cycles.”

April 2026 focused on reliability improvements, bot integration, and maintainability for chatmail/core. The team delivered end-to-end delivery guarantees for large messages, improved bot readiness by emitting IncomingMsg only after post-message arrival, enhanced broadcast channel UX by resending the last 10 messages to new members and hiding non-delivery noise, and completed configuration cleanup along with internal refactors to reduce debt and simplify operations. These changes increase platform stability, reduce support overhead, and accelerate feature delivery for customers using large messages, bots, and broadcast channels.

March 2026 monthly performance summary highlighting key business value and technical achievements across core messaging and platform readiness. Key features delivered: - Securejoin and Privacy Hardening in Messaging (chatmail/core): Upgraded securejoin protocol to v3 with end-to-end encryption of securejoin messages and removal of unencrypted headers, enhancing user privacy and reducing metadata leakage. Backward-compatible with mixed-device deployments; included domain separation fixes and token handling improvements; tests (Rust, Python) passed and manual validation performed. - Chat Reliability: Correct Message Ordering and Display: Fixed message ordering by adjusting sort_timestamp logic and ensured multi-line chat descriptions render correctly for recipients; stabilized test suite around QR securejoin and related edge cases. - Messaging Transport Visibility and Stability: Added unpublished transports support (list_transports_ex, set_transport_unpublished) and refactored transport tests; introduced TransportListEntry naming consistency; fixed an infinite loop when the folder is missing to improve reliability. - Email Privacy Enhancements: Removed unencrypted email headers in outgoing messages (In-Reply-To, References, Auto-Submitted) to minimize metadata leakage and improve privacy posture. - Release Readiness and Documentation: Prepared for release—bumped versions for upcoming API, updated docs references, and aligned release notes with the new protocol and privacy improvements. - Platform and Cross-Repository Improvements: deltachat-android gained arm64-v8a build target to improve compatibility and performance on modern devices. Major bugs fixed: - Chat ordering and display: Corrected timestamp handling and newline rendering, reducing UI inconsistencies across devices. - Securejoin edge cases: Ignore securejoin if a contact was deleted mid-process; preserve parallel securejoin flows to avoid user disruption. - Security and privacy fixes: Domain separation and dropping messages encrypted with incorrect secrets to prevent leakage and misrouting. - Transport robustness: Guard against missing folders to prevent infinite loops and ensure transport APIs behave predictably. Overall impact and accomplishments: - Strengthened privacy and metadata minimization across messaging (header removal and secure protocol upgrades) while maintaining backward compatibility. - Increased reliability of cross-device messaging with robust ordering, rendering, and transport behavior. - Expanded platform support and release-readiness capabilities to accelerate go-to-market and reduce risk in production deployments. - Demonstrated strong cross-functional collaboration and code quality through comprehensive testing, documentation alignment, and API refactors. Technologies/skills demonstrated: - Rust and Python testing for protocol and interoperability changes; cryptography best practices in secure messaging; protocol design and domain separation concepts. - Timesmearing considerations for message ordering and tests, with pragmatic risk-based improvements. - API design and refactoring (new transport APIs, naming consistency) and release engineering (version bumps, docs). - Cross-platform development: Android arm64-v8a and server-side core feature parity.

February 2026 monthly summary focusing on key features delivered, major bugs fixed, and overall impact. Delivered translations for group chat descriptions in deltachat-android, introduced bandwidth-optimized channel description broadcasting in chatmail/core with on-demand loading and per-descriptions storage, and fixed flaky transport synchronization tests to improve CI reliability. These changes improve user experience, reduce network overhead, and increase system reliability. Technologies demonstrated include Android/Kotlin development, Rust components, JsonRPC-driven metadata loading, and robust test practices.

January 2026 (2026-01) focused on reliability, privacy, and cross-device consistency in chatmail/core. Delivered configurable team profile seen-status behavior, improved cross-device message synchronization for broadcasts, and refined read status handling to prevent incorrect markings. Implemented privacy-minded past member cleanup and a robust leave/delete workflow. Hardened SMTP handling to ensure deletions execute and io restarts on new transports. Prepped DeltaChat 2.38.0 release with API changes, tests cleanup, and image handling improvements. Overall, these changes increase user trust, reduce support issues, and accelerate time-to-market for new features.

December 2025 monthly summary focusing on key features, major bug fixes, and overall impact across chatmail/core and deltachat/deltachat-android. Highlights include improved observability for SecureJoin, reliability improvements to securejoin flows, and a user-facing privacy-conscious analytics opt-in in Android. Demonstrated proficiency in instrumentation, reliability engineering, API integration, and Android UI/UX for settings.

Nov 2025 monthly summary for deltachat/deltachat-android: - Focus: Implemented QR Code Invite for Broadcast Channels to improve onboarding, security, and usability of large channels. - Delivered feature: QR Code invitations for broadcast channels with supporting constants and adjusted logic for channel-type handling. Refined visibility of specific menu items and adapter data based on channel types. - Commit reference: 2881ea71507b45262bbc9690019d73254812375d - Business impact: Faster, frictionless member invitations; improved channel security and channel-type UX consistency across the Android app. - Month: 2025-11

Month: 2025-10. Concise monthly summary focusing on key accomplishments across repositories: chatmail/core, deltachat/deltachat-android, and deltachat/deltachat-desktop. The month emphasized security hardening, user feedback clarity, and translation/locale hygiene, delivering features that reduce risk, improve UX, and lower maintenance overhead.

For 2025-09, the developer delivered a key feature to differentiate chat types in SecurejoinInviterProgress, improving onboarding analytics, with no major bugs fixed this month. The work emphasizes business value through accurate event data and enhanced user segmentation. Highlights include the API-level inclusion of chat type in the SecurejoinInviterProgress event and updating event definitions to correctly extract and emit chat type during the secure join flow, enabling more precise onboarding metrics and analytics downstream.

August 2025 highlights: Delivered targeted improvements and stability enhancements across deltachat/deltachat-android and chatmail/core. Key outcomes include a bug fix to improve link-click chat opening via address-based lookups with auto-create for new contacts; an enhancement to contact lookup that includes key contacts and prioritizes the most recently seen contact; and QA/stability upgrades including enhanced test logging, false-positive mitigation for stale tests, and a non-async mutex refactor to improve concurrency. These changes reduce user friction in chat routing, strengthen reliability, and expand test coverage—delivering tangible business value through faster issue resolution, safer releases, and smoother user experience.

Monthly Summary for 2025-07: Key features delivered: - chatmail/core: Broadcast Channels framework launched with InBroadcastChannel and OutBroadcastChannel types, a create_broadcast_channel API, and a refactor of channel creation/management. Outgoing broadcasts are encrypted and user-sent; incoming broadcasts are read-only. API, UI, and testing updated. Added support to leave channels. - deltachat/deltachat-android: Channels feature refactor, renaming "broadcast lists" to "channels" across the app, introduction of new chat types for incoming/outgoing broadcasts, and enabling leaving channels. UI and profile views adjusted to reflect channel semantics. Major bugs fixed: - chatmail/core: Verification and message processing stability improvements, including crash fixes during verification gossip, resilience when a contact verifier no longer exists, and several migration fixes for verification data. Regression tests added for verification-gossip crashes. - deltachat/deltachat-android: Channel/profile UI fixes, including removing unnecessary subtitles in InBroadcast profiles and refining avatar tap Edit button logic to show only for editable chats (not broadcasts or mailing lists). Overall impact and accomplishments: - Strengthened reliability and security of channel-based messaging across platforms, with a scalable API surface and consistent UX. Improved debugging and build visibility via enhanced test tooling and explicit build metadata. Technologies/skills demonstrated: - API design/refactor for chat types, encryption header prioritization, and robust migration handling; cross-platform UI/UX alignment; enhanced test tooling and build metadata for faster debugging and releases.

June 2025 monthly summary for chatmail/core: Delivered a targeted bug fix to Transport Configuration Integrity for Multi-Transport, ensuring ConfiguredAddr is updated only when no primary transport exists, preserving existing behavior and paving the way for multi-transport support. Introduced a new CFFI function dc_contact_is_key_contact() to identify key-based contacts for encrypted communications, with a null pointer safeguard. These changes improve reliability, security, and readiness for future expansion.

May 2025 monthly summary for chatmail/core focusing on security hardening and stability improvements, aligned with release readiness for 1.159.5. Delivered two targeted bug fixes that reduce risk, improve reliability, and enable smoother releases.

April 2025 performance summary: Across deltachat-android and chatmail/core, delivered user-facing onboarding and transport improvements, stabilized onboarding flows, and hardened CI/build processes. Key outcomes include reduced onboarding crashes, streamlined account/config setup, centralized transport configuration with clearer APIs, and improved data parsing and test coverage for vCard handling.

March 2025 performance highlights for chatmail/core: delivered substantial reliability and maintainability improvements across core messaging, IMAP configuration, and transport management. Key features delivered include a secure, centralized handle_edit_delete flow for Chat-Edit/Chat-Delete processing; new email transport APIs (add_transport_from_qr, add_transport, list_transports, delete_transport) to simplify onboarding and configurability; and a timestamp retrieval refactor to unify created_timestamp and chat_id.get_timestamp, reducing duplication and edge-case handling. Major bug fixes address mail header validity (prevent empty To header), profile transfer synchronization (ensuring key creation before transfer and added tests for self-avatar sync), and user-friendly accounts.lock error reporting. Global configuration refactors for proxy settings streamline configuration and improve TLS handling. Overall, these changes improve deliverability, observability, and developer velocity, reducing support overhead and enabling smoother onboarding for customers.

February 2025: Consolidated reliability and maintainability across deltachat-android and chatmail/core. Delivered a mix of bug fixes, feature improvements, and code quality enhancements with a focus on cross‑device UX, secure file handling, and cleaner test infrastructure. The work strengthens external sharing flows, reduces noise in notifications, and improves developer productivity through test modernization and linting.

January 2025 performance summary for deltachat and chatmail: - Delivered targeted features to improve storage efficiency, reliability, and multi-device experience across deltachat-android and chatmail/core. The work emphasized business value through reduced storage cost, improved release reliability, and enhanced user data handling. - Highlights include deduplicated attachments with preserved filenames, auto-enabling BccSelf on sync for multi-device workflows, and stability improvements in foreground service synchronization. Nightly builds across architectures were re-enabled to accelerate validation and release pipelines. - A set of core robustness and quality initiatives were implemented, including improved error handling, context checks, test organization, and config/cache hygiene, to increase reliability and developer velocity. - Overall impact: lower storage usage, smoother nightly builds and releases, better multi-device consistency, and a more maintainable codebase with faster feedback loops for developers and product teams.

In December 2024, the team delivered reliability-focused enhancements across chatmail/core and deltachat-android, strengthening CI, testing, and UI consistency, while addressing priority stability bugs. Key features delivered include CI/Build/Test reliability improvements in chatmail/core, code quality and testing infrastructure improvements, and UI consistency improvements for media previews in Android. Major bugs fixed include a panic in the receive_emails benchmark, removal of prepareMsg/state to fix InPreparation, a fallback data fetch mechanism for restricted environments, and asynchronous updates for message seen status. Overall impact: more reliable builds and faster feedback loops, uninterrupted data flow in constrained environments, and a smoother user experience. Technologies demonstrated: Rust toolchain and cargo check with feature-flag considerations, Clippy compatibility and test-failure visibility improvements, and Android background processing patterns for UI responsiveness.

November 2024 achievements across deltachat-android and chatmail/core focused on reliability, usability, and maintainability. Key outcomes include backward-compatible IMAP certificate handling, broad UI/UX polish across backup and notification flows, stronger authentication correctness with reduced false positives, iOS config cache invalidation, and safer internal API exposure with documentation improvements. These changes reduce support incidents, accelerate onboarding, and improve cross‑platform consistency and performance.

October 2024 monthly summary for chatmail/core: Delivered out-of-the-box Webxdc realtime, improved diagnostics for SMTP connectivity, and modernized text-message API usage across the codebase. These changes reduce troubleshooting time, increase user self-service capabilities, and strengthen API consistency. The work emphasized reliability, developer experience, and actionable observability.