Getting started
Requirements
- Thunderbird 151 or newer. Link Guard is developed and tested with Thunderbird 159 on macOS; other versions and platforms are expected to work but are not tested regularly.
- Messages displayed as HTML or plain text. Link Guard works in the message pane, in message tabs and in separate message windows.
Install
- Download the file
link-guard-<version>.xpifrom the latest release. - In Thunderbird, open Add-ons and Themes (menu Tools, or the ≡ menu).
- Click the gear icon and choose Install Add-on From File…, then select the XPI.
- Confirm the permission prompt.
Messages that are already open are protected right after installation; you do not need to restart Thunderbird.
Check the download (optional)
Each release also contains a SHA256SUMS file. Compare it with the checksum of your
download:
shasum -a 256 link-guard-<version>.xpi # macOS
sha256sum link-guard-<version>.xpi # Linux
Get-FileHash link-guard-<version>.xpi -Algorithm SHA256 # Windows
Official releases are built automatically from a release tag signed with the maintainer's hardware key. See Development for how that works.
Build it yourself
You can also build the XPI from source with Node.js 20 or newer:
git clone https://github.com/marco-schm/thunderbird-link-guard.git
cd thunderbird-link-guard
npm test
npm run package # creates dist/link-guard-<version>.xpi
Permissions
Link Guard asks for three permissions and no access to any website:
| Permission | Why it is needed |
|---|---|
messagesRead |
to run in displayed messages and to know when another message is shown |
scripting |
to protect messages that were already open when Link Guard was installed or updated |
storage |
to keep your approvals, blocks, lists and settings on this computer |
Your first message
Open any message with web links. Instead of clickable links you will see a notice bar at the top of the message, for example Links in this message are waiting for approval.
- Click the notice to expand it. It lists every destination host in the message, grouped into Needs attention, Not yet approved, Blocked and Approved, each with its status and any warnings.
- Check the destination independently of the email: is this a host you expect this sender to link to?
- Decide for each host:
- Allow permanently approves exactly this host and remembers the decision.
- Allow temporarily makes its links work in this message only.
- Block keeps the host's links inactive from now on.
- ⋯ approves or blocks the whole domain with all its subdomains.
Once every link is approved and none has a warning, the notice disappears. Your permanent decisions appear in Settings, where you can edit them at any time.
Tip: Clicking an inactive link does not open anything. It expands the notice and scrolls it into view so you can decide.
Where to go next
- Using Link Guard explains everything you see in a message.
- Approvals and blocks explains how decisions combine.
- Settings shows how to import lists and adjust warnings.