Thunderbird Extension

One click in Thunderbird, and Stringer takes the spammer from there.

What it does

Adds two ways to send spam to Stringer from inside Thunderbird:

Right-click any message → Send to Stringer. Works on multi-select.
A toolbar button (small red "S") in the message list, the standalone message tab, and the tab bar. Clicking it does the same thing.

Either way, the message gets moved into your stringer/queue folder on the server. Stringer notices within a few seconds and the autoresponder loop starts. There's no extra account or login — the extension uses Thunderbird's existing IMAP credentials and never talks to our servers directly.

Install

Download the latest .xpi from your account: Email accounts → Thunderbird extension.
In Thunderbird, open Tools → Add-ons and Themes.
Click the gear icon (top right of the add-ons page) and pick Install Add-on From File….
Select the .xpi file you just downloaded.
Approve the permissions when Thunderbird asks.

Requires Thunderbird 128 or newer. The extension uses Manifest V3, the modern WebExtension format.

Set up the queue folder

The extension defaults to a folder called stringer/queue. You need to create that folder on each account you plan to flag from — the extension does not create it for you (it can't tell which accounts you actually want to use it on).

In Thunderbird, right-click your Inbox → New Subfolder… → name it stringer.
Right-click the new stringer folder → New Subfolder… → name it queue.
Make sure the folder is created on the server, not in Local Folders. The new folder should appear under your account in the folder pane.

To verify: open Add-ons → Stringer → Options and click Test (list accounts). Each account should show found with the resolved server-side path. If an account shows missing, create the folder there too.

Use it

Click an obvious spam message, then either:

Right-click → Send to Stringer, or
Click the S button in the toolbar.

You'll see a notification: "Stung 1 message". The message disappears from the inbox and reappears in stringer/queue; Stringer picks it up within a few seconds. After Stringer's reply schedules, the message moves to stringer/scheduled, and once the reply sends it lands in stringer/sent.

Multi-select works on both the menu and the toolbar. The toast tells you exactly how many got moved.

Multiple accounts

If you have several accounts connected (work + personal, two Gmails, etc.), the extension is multi-account aware. It groups your selection by account and moves each batch into that account's stringer/queue folder. If one of the accounts is missing the folder, the toast tells you which: "Stung 2 messages — Folder "stringer/queue" not found on: WorkMail". Create the folder on that account and try again.

Custom folder name

If you'd rather use a different folder name, change it in Options. The extension is forgiving:

Case-insensitive: stringer/queue, Stringer/Queue, and STRINGER/QUEUE all match the same folder.
Tolerates the IMAP INBOX prefix some servers use: stringer/queue matches both /stringer/queue and /INBOX/stringer/queue.
Whitespace and leading slashes don't matter.

If you change the folder name in the extension, also change it in your Stringer dashboard under Settings → Email accounts → (account) → Queue folder so the backend looks in the right place.

Troubleshooting

"Folder ... not found" on every account

Double-check that the folder exists on the IMAP server, not in Local Folders. In Thunderbird's folder pane, the stringer/queue folder should be nested under your account name (e.g. you@example.com), not under Local Folders.

Toolbar button doesn't do anything

The button moves the currently selected message(s) when you're in the mail list, or the currently displayed message when you've opened one in its own tab. Make sure something is highlighted or open. If you still don't see anything, open Tools → Developer Tools → Browser Console and look for lines starting with Stringer:.

Notifications don't appear

Thunderbird hands notifications off to your operating system. On macOS, allow notifications for Thunderbird in System Settings → Notifications. On Linux, make sure libnotify is installed and your desktop environment supports XDG notifications.

Thunderbird shows a permission warning every install

That's normal — Thunderbird shows the permission list whenever you sideload an extension. Once approved, the extension persists across restarts.

What about Gmail and Outlook?

One-click extensions for Gmail and Outlook are on the roadmap. Until those ship, you can flag spam in those clients by:

Dragging the message into the stringer/queue folder on the server, or
Setting up an auto-rule to route spam there, or
Forwarding to your trap alias (Pro and Power tiers).