Since Tails 7.5 (February 2026), Tails tries to automatically install *Thunderbird* as [[additional software|persistent_storage/additional_software]] to improve its security.
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 As a consequence, until Tails 7.5 (February 2026), the version of *Thunderbird* in Tails was almost always outdated, with known security vulnerabilities.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.
Tails also tries to install as additional software the language package that corresponds to the language of your first session with Tails 7.5 or later. To use *Thunderbird* in another language, see how to [[use *Thunderbird* in another language|thunderbird#language]].
If the **Thunderbird Migration** dialog below appears when you start *Thunderbird*, it means that Tails successfully installed *Thunderbird* as additional software.
If the **Thunderbird Migration** notification below appears when you start Tails, it means that Tails failed to install *Thunderbird* as additional software because the [[Additional Software|persistent_storage/additional_software]] feature of your Persistent Storage is turned off.
Select **Install as Additional Software** next time you start Tails to turn on the Additional Software feature of your Persistent Storage and add *Thunderbird* to your list of additional software.
If the **Thunderbird Migration** notification below appears when you start Tails, it means that Tails failed to install *Thunderbird* as additional software for unknown reasons.