Take back your inbox. ThunderSub scans every folder in your Thunderbird mail accounts, finds every mailing list you've ever been signed up to, and gives you one place to unsubscribe from all of them — and clean up the thousands of emails they left behind.
No cloud service. No account. No one reading your mail. Everything runs locally inside Thunderbird.
| Unsubscribe & clean up in one step | Live scan progress |
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| Choose exactly what gets scanned | Track what you've left |
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Your inbox didn't get noisy overnight. It happened one newsletter, one "special offer," one forgotten signup at a time — across years and across every address you own. Cleaning it up by hand means hunting for a tiny unsubscribe link at the bottom of each email, one sender at a time.
ThunderSub turns that chore into a review queue:
- Scan once. ThunderSub walks all your accounts and folders and builds a list of every subscription it can detect.
- Decide fast. Each sender becomes a card: who they are, how many emails they've sent you, which address they're hitting, when they last wrote. Keep it or kill it.
- Unsubscribe properly. ThunderSub picks the best available unsubscribe method automatically — and can delete or file away the sender's entire back catalog in the same click.
Services that do this for webmail exist — and they do it by reading your email on their servers. ThunderSub is the desktop-native answer: your mail never leaves your machine.
- Reads the standard
List-Unsubscribeheader (RFC 2369) and detects one-click unsubscribe support (RFC 8058). - Goes further: parses email bodies (HTML and plain text) to find embedded unsubscribe links in 13 languages (English, Dutch, German, French, Spanish, Italian, Portuguese, Polish, Swedish, Danish, Norwegian, Finnish, and Russian) when senders don't play by the rules.
- Smart enough to skip quoted and forwarded content, so a newsletter your friend forwarded you doesn't show up as your subscription.
- Scans every folder across your mail accounts — skipping News/NNTP, RSS/Feeds, Junk, Trash, Sent, Drafts, and Gmail's "All Mail" duplicates by default, with folder controls to include them when needed.
- Long mailbox? Scans can be paused, resumed, or stopped at any time, and partial results are saved.
- Pick your folders: untick whole accounts or individual folders (that 20,000-message archive backup, say) in a checkbox tree. Everything new is included by default.
- Skip senders before they're even read: list patterns one per line —
phish@spammer.com(exact sender),spammer.com(domain + subdomains),*@spammer.com(domain only),*@*.spammer.com(subdomains only). - The active scope is always summarised under the Scan button, so a narrowed scan can't masquerade as a broken one.
ThunderSub doesn't just group by sender — it groups by (sender, receiving address, and account identity). If news@example.com mails both you@work.com and you+shopping@gmail.com, you'll see two cards, because those are two subscriptions that need two unsubscribes. The receiving address comes from delivery/recipient headers; the configured Thunderbird identity is tracked separately for filtering and mailto unsubscribe drafts.
For each sender, ThunderSub auto-selects the best available method:
| Method | What happens |
|---|---|
| One-click | A silent, standards-compliant POST request. You never leave Thunderbird. |
| An unsubscribe email is prepared. By default it opens as a draft for your review; flip one setting and it sends automatically. | |
| Browser | The sender's unsubscribe page opens in your default browser. |
| Embedded link | The unsubscribe link found in the email body opens in your browser. |
Did a one-click request bounce? Hit Retry and pick any other detected method from a dropdown.
Unsubscribing stops future email. ThunderSub also handles the past:
- Delete every email from a sender (to Trash — never permanently), or
- Move them to any folder — pick from a folder tree, or create a new folder on the spot,
- with per-folder control: act on the sender's emails in Inbox but leave the ones you filed in Receipts alone.
If a cleanup fails (folders move, servers hiccup), your unsubscribe still counts — the emails stay put and a Cleanup button lets you retry just that part.
Want to explore risk-free first? Flip the Dry Run toggle and every unsubscribe, delete, and move is simulated and reported ("would delete 142 emails") without touching anything — try the whole workflow end to end, then switch it off when you trust it.
- Stats at a glance: emails scanned, subscriptions found, pending / kept / unsubscribed / errors.
- Filter cards by status or by configured identity; sort by email volume or most recent.
- Keep the newsletters you actually read, dismiss dead entries, or send anything back to Pending with Review Again.
- Failed unsubscribes land in an Errors tab with the reason — nothing silently disappears.
- View any subscription to open its emails right in Thunderbird, pre-filtered by sender.
- Rescans preserve your decisions: senders you kept or unsubscribed stay that way; new senders show up as pending.
- All data lives in Thunderbird's local extension storage. Nothing is uploaded, ever.
- No telemetry, no analytics, no accounts, no third-party services.
- The only network requests ThunderSub makes are the unsubscribe actions you explicitly trigger.
- A Full Reset wipes everything it stored, any time.
ThunderSub requires Thunderbird 128 or later.
ThunderSub has not yet completed review. Its
Thunderbird add-on details page
can be accessed directly, but it is not yet listed in the add-on gallery and cannot be found through
Thunderbird's add-on search. For now, install it manually from the .xpi file:
- Open the ThunderSub add-on listing and download the
.xpifile. - In Thunderbird, open the ≡ menu and select Add-ons and Themes.
- Select the settings gear icon, then Install Add-on From File….
- Pick the downloaded
.xpifile and confirm the installation.
Because review is not yet complete, new versions may also need to be downloaded and installed manually.
git clone https://github.com/SmarakNayak/thundersub.git
cd thundersub
bash build.sh # creates dist/thundersub-<version>.xpiInstall the built .xpi using the same Add-ons and Themes → settings gear icon →
Install Add-on From File… steps above. For development, load it temporarily through
Tools → Developer Tools → Debug Add-ons → Load Temporary Add-on, then select manifest.json.
- Click the ThunderSub icon in the toolbar, then Open ThunderSub.
- Hit Scan Emails and watch the progress bar. (Pause or stop any time — results so far are kept.)
- Work through the Pending tab:
- Keep Subscription for the ones you want,
- Unsubscribe for the rest — choose what happens to existing emails (delete / move / keep) in the same dialog.
- Want to click around freely first? Switch on the Dry Run toggle in the sidebar — every action is then simulated and reported instead of executed.
| Permission | Why ThunderSub needs it |
|---|---|
messagesRead |
Read headers and bodies to detect subscriptions. |
messagesMove, messagesDelete |
The optional cleanup actions (move to folder / delete to Trash). |
accountsRead, accountsFolders |
List your accounts and folders to scan, and build the move-destination tree. |
compose, compose.send |
Prepare (and, only if you enable auto-send, send) mailto: unsubscribe emails. |
storage |
Save scan results and your decisions locally. |
<all_urls> |
Send one-click (RFC 8058) unsubscribe POST requests to whatever domain the sender specifies. URLs are validated first: public https:// endpoints only — localhost, private-network IPs, and internal hostnames are refused. |
Is it safe to let it delete emails? Deletes go to your Trash folder, never permanent deletion — and with the dry-run toggle on, nothing is touched at all. Move operations re-resolve messages by their stable RFC 5322 Message-ID right before acting, so stale data from an old scan can't delete the wrong thing.
Will unsubscribe emails be sent without me seeing them? No. By default, email-based unsubscribes open as a draft in a compose window for you to review and send. There's an explicit opt-in toggle if you'd rather they send automatically.
Does clicking unsubscribe links confirm my address to spammers?
For legitimate senders, List-Unsubscribe is the sanctioned, safe path — it's the same mechanism Gmail and Apple Mail use. For sketchy senders, prefer Keep + delete, or just dismiss the card; ThunderSub never auto-fires any unsubscribe without your click.
What happens when I rescan? New subscriptions appear as Pending. Your Keep and Unsubscribed decisions carry over. Past errors are cleared for a fresh evaluation.
Where is my data stored? In Thunderbird's local extension storage on your machine. Full Reset in the sidebar clears it completely.
manifest.json Extension manifest (Thunderbird MailExtension, MV2)
background.js Scanner, subscription store, unsubscribe + cleanup actions
popup/ Toolbar popup (quick stats + open button)
tab/ The main dashboard UI
icons/ SVG icons
No build step, no dependencies, no framework — plain JavaScript on the Thunderbird WebExtension APIs.
Bug reports and pull requests are welcome. Useful context for hacking:
- Subscriptions are keyed by
senderEmail|recipientAddress|accountIdentityAddressand stored viabrowser.storage.local. - Message references are stored as RFC 5322 Message-IDs and re-resolved to live message ids before any delete/move, because Thunderbird's numeric ids don't survive restarts.
- The UI talks to the background script exclusively through
browser.runtime.sendMessagecommands — see the handler at the bottom ofbackground.jsfor the full API surface.
ThunderSub is licensed under the Mozilla Public License 2.0.
It was inspired by BetterUnsubscribe by Luc Bennett (MPL-2.0), which pioneered convenient one-click / email / web / embedded-link unsubscribing in Thunderbird. ThunderSub extends the idea from a per-message button to whole-mailbox scanning, review, and cleanup.
ThunderSub — by Smarak Nayak. Scan it, sort it, silence it.