Roadmap

Planned work for the 2025-2026 releases of Thunderbird.

This is a list of all the primary objectives and efforts that we will be working on.

The delivery quarters provided are tentative and those timelines could change throughout the year.

Front-end Priorities

Conversation View

Priority: P1 Delivery Quarter: Q3 2025 High level objectives (non-exhaustive):

• Full thread conversation in message pane.

• Collapsible/Expandable messages.

• Thread tree visualization.

• Reply inline (optional).

Calendar UI/UX

Priority: P1 Delivery Quarter: Q2 2025 High level objectives (non-exhaustive):

• Modern event modals with flexible UI.

• Video conferencing integration.

• Maps searching integration (Google, Apple, OpenStreetMap).

• Modern HTML, markdown, plaintext editor.

• Customizable UI with sensible defaults.

• Customizable agenda and reminders.

• Better handling of unprocessed invitations.

First Time User Experience

Priority: P1 Delivery Quarter: Q2 2025 High level objectives (non-exhaustive):

• Account Hub for email, calendar, address book, feeds, and newsgroups.

• Thunderbird Sync as the first option.

• Guided discoveries of features when first accessing (welcome wizard).

• Early customization options to set the desired defaults.

• Expose important entry points like encryption and other more hidden settings.

Unified Toolbar Completion

Priority: P2 Delivery Quarter: Q3 2025 High level objectives (non-exhaustive):

• Remove old customizable UI toolbar.

• Unifying controls for spaces, standalone dialogs, and windows.

• Add overflow space.

• Add more buttons and elements (spin buttons, separators, button groups, etc).

• Menu position.

• Rows.

• Drop the App Menu!

Tabs

Priority: P2 Delivery Quarter: Q3 2025 High level objectives (non-exhaustive):

• Spaces and tabs rebuild, with each space handling their own tabs.

• Standalone windows per space without the need of having the "mail" space.

OS System Tray

Priority: P2 Delivery Quarter: Q4 2025 High level objectives (non-exhaustive):

• Same tray code for Linux, Windows, and macOS.

• Unread indicator and counter.

• Minimize to tray.

• Start minimized.

• Compose action per account.

• Open settings.

• Quit action.

Native OS Notifications

Priority: P2 Delivery Quarter: Q4 2025 High level objectives (non-exhaustive):

• Quick actions to reply, delete, mark messages.

• Pause notifications for # time.

• Manage notifications per account.

• Focus modes.

Compose Window

Priority: P3 Delivery Quarter: Q1 2026 High level objectives (non-exhaustive):

• Drop the C++ editor code.

• Implement a modern JS editor component that can be reused in calendar, tasks, and any other text area field that needs it (signature, address book notes, etc).

• Link previews.

• Rich text with advanced features.

• Markdown support and preview.

• Native emojis support (unicode).

• Mentions support.

Settings UI

Priority: P3 Delivery Quarter: Q1 2026 High level objectives (non-exhaustive):

• Modal dialog, because a settings tab doesn't make sense.

• More sections and tabs for an intuitive discovery path, drop the never ending single pages.

• All "Appearance" settings in one page, including native themes (follow system, light, dark)

• Application settings and Account settings should be in the same place.

• "Labs" section for listing experiments

Tasks

Priority: P3 Delivery Quarter: Q2 2026 High level objectives (non-exhaustive):

• Easier onboarding! Store them in the profile and sync them if there are no supported calendars.

• Use open specs to allow interoperability.

• Be opinionated with what we do here.

• Modern UI.

• Show tasks in the calendar.

• Kanban board.

• Integrate into emails, address books, and other areas.

Home Space

Priority: P3 Delivery Quarter: Q3 2026 High level objectives (non-exhaustive):

• Stats!

• Quick links to common actions.

• Summarization of accounts.

• Blog listing (feed).

• Suggested actions.

Chat Design Kickoff

Priority: P3 Delivery Quarter: Q4 2026 High level objectives (non-exhaustive):

• Create design plan

• Identify areas with technical debt

• Prioritize existing features

• Prioritize new features

Back-end Priorities

Exchange Email

Priority: P1 Delivery Quarter: Q1 2025 High level objectives (non-exhaustive):

• Full support of email operations.

• Full support of account creation.

Global Database

Priority: P1 Delivery Quarter: Q2 2025 High level objectives (non-exhaustive):

• SQLite based.

• Rust interfaces.

• Migrations.

• Rollbacks.

• Build in parallel and populate it alongside the current database.

A New Email Encryption

Priority: P1 Delivery Quarter: Q1 2026 High level objectives (non-exhaustive):

• Thunderbird should be the champion of encryption and propose a new open path.

• Making it easier for non-technical users to use a reliable encrypted solution.

Sentry

Priority: P2 Delivery Quarter: Q1 2025 High level objectives (non-exhaustive):

• Add Sentry SDK & Initialise with DSN

• Add channel/environment

• Leverage default error capturing mechanisms

• Add Custom Breadcrumb for one component

• Configure reporting

• Test

• Document for future consumption in other components

Performance

Priority: P2 Delivery Quarter: Q2 2025 High level objectives (non-exhaustive):

• Audit current startup code.

• Slowly rebuild it.

• Create performance profiles to measure startup performance impacts.

• Implement the "�start minimized" back-end.

• Take ownership of the "primary password"� process

Exchange Calendar

Priority: P2 Delivery Quarter: Q3 2025 High level objectives (non-exhaustive):

• Integrate the exchange calendar protocol.

• Use it as a way to rebuild/improve the current calendar protocol.

• Support exchange-specific features.

Exchange Address Book

Priority: P2 Delivery Quarter: Q3 2025 High level objectives (non-exhaustive):

• Integrate the exchange address book protocol (maybe it uses carddav?)

• Support exchange-specific features.

• Fetch users' profile pictures.

Exchange Graph API

Priority: P3 Delivery Quarter: Q1 2026 High level objectives (non-exhaustive):

• Audit what can be supported via GraphAPI.

• Build a parallel protocol to A/B test against EWS.

Notes

Priority: P3 Delivery Quarter: Q2 2026 High level objectives (non-exhaustive):

• Store notes in the profile and in Sync.

• HTML, markdown, plaintext editor.

• Share notes via Send.

• Copy the Google approach (create notes for this event).

• Potential Pro offering (cloud notes with shared access like Etherpad).

• Potential syncing through IMAP.

Maintenance Priorities

Support URLs

Priority: P1 Delivery Quarter: Q1 2025 High level objectives (non-exhaustive):

• Plan and implement an efficient and standard approach to links within the application

Better logging/diagnostics

Priority: P1 Delivery Quarter: Q1 2025 High level objectives (non-exhaustive):

• Implement Sentry and telemetry to capture data that will help us prioritize response to issues based on frequency.

• Add or change logging tools to make it easier for the majority of users to provide logs.

Fluent Migration

Priority: P2 Delivery Quarter: Q2 2025 High level objectives (non-exhaustive):

• Assign a small migration effort every 2 weeks to each developer.

Complete Glean testing and uplift

Priority: P2 Delivery Quarter: Q2 2025 High level objectives (non-exhaustive):

• Complete the project.

• Validation that data is being captured as expected.

• Help services consume the data.

Hardening

Priority: P2 Delivery Quarter: Q3 2025

Fuzzing and Monkey testing

Priority: P2 Delivery Quarter: Q3 2025 High level objectives (non-exhaustive):

• Work with Rob to create scripts, VMs, checking tools etc that we can have running regularly to catch edge cases much sooner without users having to experience then report.

Re-implement Movemail

Priority: P3 Delivery Quarter: Q3 2025 High level objectives (non-exhaustive):

• Reimplement the ability to use Movemail in Thunderbird.

• No account creation feature for now.

Removal of the *Overlay.js files

Priority: P3 Delivery Quarter: Q4 2025 High level objectives (non-exhaustive):

• Replace overlay files with modules and system modules.

• Defer non-DOM operations to system modules.

• Lazy load modules when needed.

Out of scope

As we focus on the P1s, we need to always account for the dozens of other features we currently ship in Thunderbird.

These features always require maintenance, regressions and security fixes, and upstream porting.

What we won't do during this cycle is adding new features or rebuilding big chunks of code outside of the prioritized components and efforts listed in the front-end and back-end tables.

These "outsiders"" listed here are a way to highlight low priority maintenance efforts that can happen during the year, but that won't (shouldn't) take us away from the top priorities.

Feeds

• Inheriting the email UI for now is acceptable.

• It needs a complete UI and UX overhaul.

Newsgroups

• Low user adoption.

• Inheriting the email UI for now is acceptable.

Add-ons page

• A very large effort that will happen in the future.

• It's tied to the website rebuild.

Address Book space

• More improvements are needed but the current state is superior to other areas.

• A substantial rebuild happened 2 years ago.

OpenPGP and S/MIME integration

• Currently in a usable and enough stable state.

• Dedicating security fixes during this cycle.

• The UI saw some improvements in the past few years.

Message Filters

• They will need to be rebuilt from scratch.

• Tied to the new database implementation for easier message move/copy handling.

Import/Export

• Sync will make the need to import/export the whole profile hopefully uncommon.

• After that we should disable exporting the entire profile because it fails when dealing with large sizes.

Account Settings

• They should be integrated into the Settings space.

• It needs a lot of UI/UX rethinking.