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 Tailsrelease, 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 As a consequence, until Tails 7.5 (February 2026), the version of *Thunderbird* in Tails was almost always outdated, with known security vulnerabilities.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.
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 Softwarefeature 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.