Mozilla is planning a major UI redesign for its Thunderbird email client this July.

“Why does Thunderbird look so old?”

According to Thunderbird project lead Alessandro Castellani, this is one of the most frequently asked questions about Thunderbird (along with “Is Thunderbird dead?”). And that’s what he’s trying to definitively answer in a new blog post about Thunderbird’s planned 2023 release, codenamed Supernova.

Among other features, the release of Supernova will include a redesign of the Thunderbird user interface. Castellani did not share screenshots, but indicated that the new user interface will be “simple and straightforward”and geared primarily towards new users. For “power users”, the interface will also be “flexible and adaptable”so that people who prefer the way Thunderbird looks now can “keep the familiarity they like”.

Supernova will also include several other major changes, including a redesigned calendar and support for Firefox Sync.

Aside from the redesign news, the blog post is worth a read if you’re wondering what the team is doing to combat software technical debt, or if you want to know why app development seems to be moving so slowly (developers spend a lot of time they just keep track of changes to the original stream from Firefox, since the browser still serves as the basis for Thunderbird email rendering). This post is also helpful if you need to brush up on the long and complicated relationship between Thunderbird and Mozilla.

Mozilla used to support Thunderbird alongside the Firefox browser, but in the modern era it wasn’t always clear who was responsible. Mozilla executives wanted to spin off Thunderbird back in 2007, and in 2012 the company moved to a more community-driven development model.

This decision, according to Castellani, was a “blessing and a curse”that placed Thunderbird in the position it is in today. Community contributions to Thunderbird kept the project alive, but the lack of central control “resulted in an inconsistent user interface with no consistent user experience”and led to long stretches of time when the application was not updated at all.

Today, Thunderbird’s development is still partly done by community developers, and the project relies heavily on user donations. But it’s also coming back somewhat to Mozilla through a “growing group of paid employees”at a Mozilla subsidiary called MZLA Technologies. It is these employees who are currently setting Thunderbird’s roadmap, working to help it get rid of technical debt, and hoping to expand its user base with a new Android client based on the K-9 Mail app.

A redesigned Thunderbird user interface is currently slated for Thunderbird 115 due for release in July.