A new version of *Thunderbird* is released in Debian shortly after each Tails release, because both *Tails* and *Thunderbird* follow the [[release calendar of *Firefox*|https://whattrainisitnow.com/calendar/]]. As a consequence, until Tails 7.5 (February 2026), the version of *Thunderbird* in Tails was almost always outdated, with known security vulnerabilities.
By installing *Thunderbird* as additional software, the latest version of *Thunderbird* is installed automatically from your Persistent Storage each time you start Tails.