Link Guard for Thunderbird

Link Guard is a Thunderbird add-on that keeps web links in email inactive until you approve where they lead. Every displayed message gets a compact notice that lists the destination hosts, flags suspicious links, and lets you allow or block each host for this message only or permanently.

Nothing leaves your computer: Link Guard checks messages locally, ships no trust list and sends no mail content or link targets anywhere.

What it does

• Holds every web link until you decide. A link becomes clickable only after its destination host is approved, either for the current message or permanently.
• Shows where a link really goes. Links whose text does not name their destination show the real host next to them, and the notice lists every destination in the message.
• Warns about phishing patterns. Lookalike and internationalized domains, misleading link text, credentials in the URL, IP addresses, public URL shorteners, script code in the link and redirects to sites you have not approved get prominent warnings and need a deliberate approval of the exact host.
• Lets you decide at the right scope. Approve or block one exact host (login.example.org) or a whole registrable domain with all its subdomains (*.example.org).
• Supports lists and your own rules. Import allowlists and blocklists from files or HTTPS sources, and add warning rules as regular expressions.

What it is not

Link Guard is a warning aid. It does not scan files or websites for malware, it does not check who sent a message, and it cannot see where a link redirects after you open it in your browser. An approved host can still serve harmful content. See Security model for the exact boundaries.

Documentation

At a glance

This documentation describes the latest release; the version is shown at the top of each page. The changelog lists which release introduced each change.