Thunderbird has gone through a lot of changes recently, notably through the Supernova release, which was published in the summer of 2023, and is still rapidly evolving. Part of the work we have been doing in the background to enable this evolution is adding support for Rust to the Thunderbird code base. In this talk, we'll tell the story of how we achieved this and what lessons we learned along the way. We’ll also show how we’re using Rust to both improve the existing code architecture, and build new features for Thunderbird such as support for Microsoft Exchange.