What is the "Libre Email Client" add-on and how can I use it?

Libre Email Client is a browser extension that turns your browser into a full-featured IMAP email client. It syncs mail from any IMAP server to a local Maildir store using a compiled WASM IMAP core — no external email app required.

How to use it:

1. Install the extension and open the welcome wizard (it appears automatically on first launch).
2. Choose your connection mode — either the built-in native bridge (default, no setup) or an external WS/TS bridge (for network/shared setups).
3. Add your IMAP account(s) — enter host, port, credentials, and optionally set a master password to encrypt stored passwords.
4. Sync — mail syncs automatically on a schedule, or manually via the Sync buttons (Dir/Account) in the footer.
5. Read and manage mail — browse folders in the left pane, search server-side, read messages in the preview pane, and use the toolbar for layout, explorer, and settings.

The extension supports multiple accounts, conversation threading, message filters (move/stop), a badge unread counter, a file explorer for your local mail store, and optional Spam/Archive/Trash button overrides that save .eml files to a local directory (requires the native client).

What's new in this version?

Please check the Logs section.

Do I need to install a native client to use this extension?

Only if you want to use the "move outside of Maildir" features (Spam, Archive, Trash button overrides that save .eml files to a local directory) or if you cannot run a permanent WS/TS bridge accessible from your browser. For users on a network, it is recommended to use a WS/TS bridge so that all users on the network can install and use the email client without manually installing the native client. The native client is available in two runtimes: NodeJS (com.add0n.node) and BunJS (org.webextension.bun).

How do filters work?

Filters are evaluated top to bottom, and the first match wins. Each filter has a query rule and an action. The query syntax supports fields like subject:, from: (or sender:), to:, and body:, combined with and, or, not, and parentheses. A bare word matches anywhere. Each line in the query is a separate rule — a message is acted on if it matches any one line (lines act as OR). An empty query matches every new message.

There are two actions:

• Move (default): moves the matching message to a destination server folder. You can optionally create the folder if it is missing.
• Stop: leaves the message where it is and stops further filter evaluation for that message. This is a guard rule — place it above the filters it must shield, and their queries can stay simple (no not chains needed).

Filters run in three contexts: the sync panel's filter row (a single pick reports matches, renames nothing), the "use all filters" walk, and the post-sync pass (which fires on both clean and failed sync runs).

Can I have multiple accounts?

Yes. You can add as many IMAP accounts as you need from the Options page → Accounts tab. Each account has its own label, IMAP settings, and credentials. You can designate one account as the "primary" account. Accounts can be reordered with drag & drop. The account selector in the mail client toolbar lets you switch between them, and each account syncs independently.

What are the options I have in the toolbar?

The mail client toolbar (the bar above the message list) contains:

• Search box — server-side IMAP search with from:, to:, subject:, since:, etc. Prefix with all: to search all folders; without it, search is scoped to the current folder. Press Enter to run, Esc or the ✕ button to clear.
• Account selector — switch between configured accounts.
• Layout toggle — switch between horizontal and vertical preview layout.

The footer bar contains:

• Explorer (E) — opens the file explorer to browse your local Maildir storage.
• Sync combo box — three buttons:
  • Dir (D) — sync the selected folder.
  • Account (Y) — sync the entire selected account.
  • Open (N) — open the sync interface panel on a new tab (without syncing).
• Activity logger — shows sync/filter activity; the ✕ cancels a running action or dismisses a failed line.
• Settings gear (G) — opens client settings: "Show unread only", "Show single messages" (flat vs. threaded), and "Expand sub dirs".

Keyboard shortcuts: Alt+1 focuses the folder pane, Alt+2 the message list, Alt+3 the preview pane.

What is the WS/TS bridge and why do I need it?

The extension's IMAP core runs as WASM inside the browser, but browsers cannot open raw TCP/TLS sockets. The WS/TS bridge is a small intermediary that receives WebSocket connections from the extension and tunnels them as raw TCP/TLS to your IMAP server. You have two options:

1. Built-in (native messaging) — the extension boots a local bridge inside the native messaging sandbox automatically. No user-visible process is spawned. This is the default.
2. External WS server — you run a WebSocket server (a sample zero-dependency Node.js script ships with the extension) and point the extension at its URL. This is recommended for network setups where multiple users share one bridge, or when you cannot install native apps.

The protocol is simple: the client sends {op:'open', host, port, secure} as a text frame, the server replies {op:'ready'} or {op:'error'}, then tunnels the stream as binary frames. The bridge can be written in any language.

What is the master password?

The master password is an optional password that encrypts your stored account passwords. When set, all account passwords are saved in encrypted form (enc1...). The master password itself is kept in session storage only, so you are asked for it once per browser session. Setting, changing, or removing the master password automatically re-encrypts all saved passwords. If you remove it, passwords are decrypted back to plain text.

How does the badge counter work?

The badge counter shows the total unread count across all badge-enabled accounts on the extension icon. It reads only the local Maildir store (no server round-trip) — every account's unread count comes from the message files themselves. By default, an account's badge counts its INBOX; you can pick a different folder or a search query to count query-matched unread mail across all folders. An age limit restricts the count to unread mail newer than the chosen window. A check runs after local edits and after each landed sync run.

What is the file explorer?

The file explorer is a built-in browser for your local Maildir storage. It lets you browse the folder tree, download files, rename, delete, create new folders and maildirs, and import files. Browsing is read-only; write actions ask for write permission on first use. The explorer is useful for inspecting the raw mail store, importing existing .eml files, or troubleshooting sync issues.

How does automatic sync work?

There are three automatic sync mechanisms:

1. Periodic full sync — every account is fully synced (every folder) at a configurable interval (default 15 minutes, minimum 5). A manual full sync resets that account's timer.
2. Dirty (partial) sync — after a local edit (flag change, move, delete), the changed folders are re-synced with the server after a configurable delay (default 60 seconds, minimum 10). This coalesces bursts of edits.
3. Idle detection — when the computer becomes active again after being idle or locked (~10 minutes away), the badge counter's folders are synced and the badge recount follows.

All automatic syncs can be disabled with the master switch. Manual syncs from the client or sync interface always work regardless.

What storage options do I have?

You can choose between:

1. Browser storage (OPFS) — the default. Synced mail lives in the extension's own private storage. No directory picker or permission needed, but the mail is tied to the browser profile (removing the profile or extension removes the mail).
2. Custom directory — the Maildir tree is stored in a folder of your choice via the File System Access API. The directory handle is remembered across browser restarts, but a lapsed permission has to be re-granted. This is useful for keeping mail outside the browser profile or sharing a store.

What are the Spam, Archive, and Trash button overrides?

By default, the Spam, Archive, and Trash buttons perform standard IMAP actions (marking, moving to server folders). You can override each button to instead save a copy of the selected emails as raw .eml files to a local directory of your choice, then optionally delete them from the IMAP server. This requires the native client to be installed, as it needs to write files on your local filesystem. Each override can be configured independently with a destination directory and an optional "Delete from IMAP after saving" checkbox.

How does server-side search work?

The search box in the toolbar performs server-side IMAP SEARCH queries. Supported fields: from:, to:, subject:, since:, body:, and more. A bare word matches anywhere. Combine terms with and, or, not, and parentheses. Prefix with all: to search across all folders; without it, search is scoped to the currently selected folder. Press Enter to run the search, Esc or the ✕ button to clear and return to the folder view.

What keyboard shortcuts are available?

• Alt+1 — focus the folder pane
• Alt+2 — focus the message list
• Alt+3 — focus the preview pane
• E — open the explorer
• D — sync the selected folder
• Y — sync the selected account
• N — open the sync interface
• G — open client settings
• ↑/↓ — navigate within the focused pane
• →/← — expand/collapse folders
• Enter — open selected email / open selected folder
• Space — check/uncheck selected email
• Ctrl+A — select all emails

Note: shortcuts are inert while an email body iframe has focus (key events from inside a sandboxed iframe never reach the page).

How do I back up my preferences?

The Options page has a "Preferences backup" section with Export and Import buttons. Export downloads every setting stored by the extension — accounts, filters, UI preferences, and action overrides — as a JSON file. Import restores such a file; you are asked whether to merge with current settings or replace everything. Account passwords are included only when a master password encrypts them, or when you explicitly agree to export them in plain text.

What is the welcome wizard?

The welcome wizard is a three-step setup guide that appears on first install:

1. Mode choice — choose between a remote bridge (no installation, ideal for shared/network setups) or a local native client (required for local file operations).
2. Bridge or native client setup — configure the WS/TS bridge URL or install the native client.
3. Account details — enter your IMAP account credentials and optionally set a master password.

The wizard can be re-opened from the Options page.