Privacy
Link Guard is built to work without sending anything anywhere.
What stays on your computer
- Your mail. Messages are inspected inside Thunderbird. No message content, link, host name or decision is sent to anyone.
- Your settings. Everything is stored in Thunderbird's local extension storage for your profile. Nothing is synchronised to a cloud service.
- Domain checks. Lookalike detection and whole-domain scopes use the Public Suffix List bundled with the add-on. Link Guard never looks up domains online.
Link Guard contains no telemetry, no analytics and no update checks. It does not update itself either: new versions are installed from the releases page like the first one.
What is stored
| Stored item | Content |
|---|---|
enabled |
whether protection is on |
showDestinations |
whether destination labels are shown next to links |
customAllowedHosts |
your exact permanent approvals |
blockedHosts |
your exact blocks |
broadAllowedDomains |
your whole-domain approvals |
blockedDomains |
your whole-domain blocks |
importedLists |
imported host lists: name, type, category, entries, source URL, enabled state, update settings and the time and result of the last automatic update |
disabledWarnings |
built-in warnings you switched off |
customWarnings |
your own warning rules |
warningLists |
imported warning lists: name, rules, source URL and enabled state |
Temporary approvals are kept only in memory for the message on screen and are discarded when you show another message.
Removing Link Guard in Add-ons and Themes removes its stored data with it.
Network requests
Link Guard makes network requests only to list sources that you add yourself:
- when you click Check remote list or Review remote update in Settings, and
- for automatic updates of enabled remote blocklists, about once a day per list.
Each request:
- goes over HTTPS to exactly the URL you entered, without following redirects,
- carries no cookies or other credentials and no referrer,
- contains nothing about your mail, your links or your decisions.
Like any web request it reveals your IP address to the server of the list. Because the
request is a cross-origin request, the server also sees Link Guard's per-installation
extension origin (a random identifier of the form moz-extension://…). Add lists only
from sources you trust, and switch off Update automatically for a list if you do not
want daily requests.
Opening an approved link is done by your browser, not by Link Guard, and is subject to your browser's own privacy settings.