Expose option to import profile from backup. (Bug 1731064)
New address book UI: During the 91 cycle we already implemented the start of a new UI, in about:addressbook. The new address book lives in a tab. During the next cycle we will bring this implementation up to par with the old address book, and remove the old one. (Bug 1705276)
Improved storage: The current backend needs to be changed to support vCard data properly; e.g. arbitrary number of email addresses. Bug 469209
Non-standard data fields like “preferDisplayName” and “ChatName” should be dropped or moved out of the address book. Bug 1727298
Consider dropping the read-only OSX address book, and switch users over to using their read-write iCloud calendar through CardDAV.
Replace Mork in panacea.dat (folder metadata) (bug 418551)
Replace Mork for message index (bug 11050): create a global message index backed by a real database. Currently the index of messages is per folder (and based on Mork). This causes severe limitations to implementing a proper conversation view of messages. This work is tracked in bug 1572000.
IMAP notes? Storing text notes on the IMAP server would be useful, and the feature is low hanging fruit not necessarily very hard to implement. Tracked in bug 713843.
Printing CSS (mostly) improvements: make the printed mails/calendars/address books look nice.
Spaces toolbar: Implement an easier and more convenient way to move between the different parts of the application (mail, calendar, tasks etc.) Tracked in bug 1665511.
Rebuild the message header. The message header has a bit of messy source code, and with the removal of the customizable toolbar, it seems necessary to do a good clean up and rethink the UI to better highlight sections and make the whole area properly responsive. Mock-up:
Mail data utilization and integration
detect structured data (JSON-LD), allow acting on that data (see schema.org, xref KItinerary) — e.g. let you add flight data into your calendar directly
detect micro-formats [related to smart-widgets]
detect the most common free texts (especially: times and dates), and allow inline viewing of calendar schedules for that time, or contact information for a known contact in your address book etc.
improved support for drag-n-drop as well as copy-paste of many data types: mail data, events, contacts
Implement a new icon theme with symbolic and hicolor variation, and predefined color schemes for the folder pane icons users can select.
Make more areas of the UI be sensitive to the Density pref.
Implement a UI pref to change the font size of the entire app.
Implement a more solid design system with consistent colors, spacings, font-sizings, etc., in order to be more independent from the variable changes coming from m-c and reduce the amount of visual regressions and upstream syncs.
Support mailing list management headers (List-Unsubscribe, List-Archive, List-Post, List-Archive). Bug 29041.
Firefox has officially deprecated the old style localization system since October 2019. Thunderbird should do the same: i.e. adding/changing strings only allowed for Fluent strings, with properties/dtd files basically freezed.
Add iframes to the Thunderbird UI where WebExtensions need to load custom content, similar to the sidebar of Firefox. This could be added as a dedicated API or per use-case to the individual APIs (calendar, addressBook, mailTabs), see bug 1693543.
Add a DNS API for advanced DNS requests (not just A records).
Add a Sessions API to allow WebExtensions to store/access session data (similar to what is provided by Firefox).
Work on internal message handling, so WebExtension can identify messages across sessions with the same id.
Allow for additional customization and add an overflow container for action buttons, if UI space is exhausted.
Support better theming/UI integration of WebExtension option tabs
Add an API for calendar access and providing new calendars to Thunderbird (bug 1627205)
Rework the contacts APIs to fix existing gaps like missing photo access, align with the new address book and permit add-ons to provide their own address books.
Figure out a way forwards for file system access (Chrome FileSystem API?) together with Mozilla core.
Encrypt if possible (guided TOFU): Like SSH, we should move more towards trust on first use (TOFU). This would be more feasible if all incoming keys were automatically collected for possible usage later (Bug 1667564) - at the moment without chores for the user, it does not work since the keys are not “known”, even if they have been sent to you. Bug 135636/ bug 1627956.
Publish to keyserver: We should allow users to publish their key on the openpgp keyserver for others to discover. Bug 1731232