🇬🇧 English | 🇫🇷 Français

Filter & Move Messages — Thunderbird Extension

Thunderbird 128+ extension to automatically filter and move messages based on custom rules.

Features

Smart Filtering

• Email field filtering: From, To, Cc, Bcc (contains, is, not contains, is not)
• Address book filtering: checks if the sender is in a Thunderbird address book
• Subject and body filtering
• Smart Filter: advanced Gmail-like syntax (FROM contains john@mail.com AND SUBJECT contains invoice)
• Multiple conditions: AND mode (all conditions) or OR mode (at least one condition)
• Brace support for values containing spaces: SUBJECT contains {my value}

Optimized Execution

• "Run all filters": scans only the INBOX of selected accounts (not subfolders)
• "Run filters on this folder": runs on the selected folder(s) in Thunderbird (multi-selection supported)
• First matching filter wins: each message is processed by the first matching filter (priority order)
• Batch moves: a single API call per destination for better performance
• Anti-loop protection: never moves to the source folder

Per-Filter Account Selection

• Each filter has its own account selection (all or individual)
• Precisely target which inboxes to scan

Administration Page (2 tabs)

"Apply Filters" Tab

• Automatic execution on new message arrival
• Manual execution
• Execution after junk mail check
• Option to remove own email addresses

"Filter Management" Tab

• Toolbar: New / Delete / Clone / Edit / Export / Import
• Adaptive filter table (fills available height) with 4 columns:
  • Filter (name)
  • Smart Filter (condensed syntax)
  • Destination (target folder)
  • Active (checkbox)
• Drag reordering: ⤒ Top / ↑ Up / ↓ Down / ⤓ Bottom
• Targeted execution: all filters or selected filter

Filter Editor (Modal Window)

• Filter name
• Application options (new message, manual, after junk check)
• Per-filter account selection
• Match mode: AT LEAST ONE condition / ALL conditions
• Dynamic conditions with +/- buttons (field, operator, value)
• Browsable folder tree with search to choose destination
• Real-time Smart Filter preview
• Editable Smart Filter textarea with bidirectional sync

Toolbar Popup

• Run all filters — scans configured accounts' inboxes
• Run filters on this folder — runs on selected folder(s)
• Filter management — opens the administration page

Logging

• Concise per-folder summary with per-filter and per-message detail (author + subject)
• No verbose logging in normal operation

Project Structure

thunderbird-filter-move-mail/
├── addon/                          # Thunderbird Extension
│   ├── manifest.json               # Manifest V2 (TB 128+)
│   ├── _locales/
│   │   ├── ar/messages.json        # Arabic
│   │   ├── de/messages.json        # German
│   │   ├── en/messages.json        # English
│   │   ├── es/messages.json        # Spanish
│   │   ├── fr/messages.json        # French (default)
│   │   ├── it/messages.json        # Italian
│   │   ├── ja/messages.json        # Japanese
│   │   ├── nl/messages.json        # Dutch
│   │   └── zh_CN/messages.json     # Chinese (Simplified)
│   ├── background/
│   │   ├── background.html         # Background page
│   │   └── background.js           # Main script (events, messaging)
│   ├── popup/
│   │   ├── popup.html              # Toolbar button popup
│   │   ├── popup.css
│   │   └── popup.js
│   ├── options/
│   │   ├── options.html            # Administration page (2 tabs)
│   │   ├── options.css
│   │   └── options.js
│   ├── filter-editor/
│   │   ├── editor.html             # Filter editor modal
│   │   ├── editor.css
│   │   └── editor.js
│   ├── lib/
│   │   ├── storage.js              # Persistence (browser.storage.local)
│   │   ├── filter-engine.js        # Filter engine (matching + execution)
│   │   └── account-manager.js      # Account/folder management
│   └── icons/
│       ├── filter-16.svg
│       ├── filter-32.svg
│       ├── filter-48.svg
│       └── filter-128.svg
├── releases/                       # .xpi files (releases)
├── updates.json                    # Auto-update for Thunderbird
├── LICENSE                         # MIT
├── README.md                       # English documentation
└── README.fr.md                    # French documentation

Installation

From .xpi file (recommended)

1. Download the .xpi file from Releases
2. Open Thunderbird → Menu → Tools → Add-ons
3. ⚙️ → Install Add-on From File → Select the .xpi

Development mode

1. Open Thunderbird
2. Menu → Tools → Add-ons
3. ⚙️ → Debug Add-ons → Load Temporary Add-on
4. Select the addon/manifest.json file

Smart Filter Syntax

FROM contains john@example.com AND SUBJECT contains invoice
TO is admin@company.com OR CC contains team
FROM in_addressbook
BODY contains {important keyword with spaces}

Fields	FROM, TO, CC, BCC, SUBJECT, BODY
Operators	contains, not_contains, is, is_not, in_addressbook, not_in_addressbook
Connectors	AND (all conditions), OR (at least one)
Braces	{value with spaces} for multi-word values

Thunderbird APIs Used

API	Usage
accounts	List accounts and identities
addressBooks	Check contacts in address books
contacts	Quick contact search
messages	List, read, and move messages
mailTabs	Get selected folder(s) (multi-selection TB 128+)
storage	Store filters and preferences
i18n	Internationalization (9 languages)

Permissions

Permission	Usage
accountsRead	Read accounts and folders
addressBooks	Access address books
messagesRead	Read messages
messagesMove	Move messages
messagesDelete	Delete messages
storage	Local storage for filters and preferences

Languages

• 🇫🇷 French (default)
• 🇬🇧 English
• 🇩🇪 German
• 🇪🇸 Spanish
• 🇮🇹 Italian
• 🇳🇱 Dutch
• 🇯🇵 Japanese
• 🇨🇳 Chinese (Simplified)
• 🇸🇦 Arabic

Compatibility

• Thunderbird 128+ (Manifest V2)
• Tested with Thunderbird 147

License

MIT

Author

Mikael Maunier — @mmaunier