Cascading server search with always-visible progress (Thunderbird for Android)

[mail4mail]

 Problem
 Searching in Thunderbird for Android only searches messages already synced to the device.
 The optional server search is hidden behind a small toolbar icon, only searches the single
 folder you started from, and gives almost no feedback: with no local hits you see a blank
 screen, progress texts get overwritten while results arrive, and failures only flash as a
 short toast. Users regularly conclude that "search is broken" (see the blank-screen reports).

 Proposal
 1. When a manual search finds nothing locally, show a clear message with a tappable prompt
 to search on the server (instead of a blank screen).
 2. Let the server search cascade: current folder first, then the remaining folders of the
 account, then the other accounts - sequentially, skipping accounts whose backend cannot
 search server-side (e.g. POP3), and continuing past folders that fail.
 3. Show a persistent status bar with a spinner above the result list for the whole duration:
 "Searching <account> / <folder> on server (3 of 14)" and "Downloading message 2 of 8 from
 <folder>". End states stay visible in the list ("No messages found on the server",
 "Remote search failed").

 Working prototype
 I have a working implementation on a fork (branch `feature/cascading-server-search`):
 https://github.com/JustNotesa/thunderbird-android/tree/feature/cascading-server-search
 including screenshots and a test APK in the releases. Happy to adapt it to maintainer
 feedback and to the new message list implementation, and to submit it as a PR once the
 feature is accepted. The implementation was built with AI assistance (Claude).

[Jon]

Thanks for submitting an idea to the Mozilla Connect community! Your idea is now open to votes (aka kudos) and comments.

[mail4mail]

Update: the two underlying bugs are filed as thunderbird/thunderbird-android#11377 (blank search result screen) and thunderbird/thunderbird-android#11378 (server search progress disappears). A current test build of the prototype, rebased onto main, is available here: https://github.com/JustNotesa/thunderbird-android/releases/tag/search-preview-2

[mail4mail]

Update, October 2026: the prototype has grown since the original post.

New:
- The server search starts by itself after the local search and can be restarted by pulling down. It also works from the Unified Inbox.
- The first row of the results shows which folder is being searched, what the search is waiting for, and how it ended. Folders that could not be searched are reported.
- Each result shows its account and folder; tapping it opens the folder.
- Searching for several words finds messages that contain all of them. The search text stays visible and can be edited.
- Recent searches are suggested (stored on the device only, can be switched off).
- Optional extra step: also search the message contents on the server.

Code: https://github.com/JustNotesa/thunderbird-android/tree/feature/cascading-server-search
Test build: https://github.com/JustNotesa/thunderbird-android/releases/tag/search-preview-3
Related GitHub issues: thunderbird/thunderbird-android #649 (server-side search on all folders), #4513 (improve search), #11377 and #11378 (the two underlying bugs).

[Jon]

Thanks for submitting an idea to the Mozilla Connect community! Your idea is now open to votes (aka kudos) and comments.