Open source software developer Mozilla Foundation has launched a new subsidiary, Mozilla Messaging, which will focus on the development of Thunderbird 3 for the non-profit organization.

Thunderbird is the foundation's free, open source email client, currently used by millions of users all over the world.

It is hoped that the latest iteration of the application will deliver noticeable improvements over its predecessors, including an integrated calendar, better search functionality and enhancements to the user experience.

David Ascher, chief executive of Mozilla Messaging, said that the new organization will work on Thunderbird 3 as part of a wider community of contributors from across the globe.

"Every one of us is committed to building a great email product that people will love to use and that serves as the foundation for choice in a critical area of internet software."

As well as Thunderbird, the Mozilla project also develops and maintains Firefox, the most popular open-source internet browser currently available to internet users.

Since its launch in 2004, Firefox has been downloaded more than 400 million times. Mozilla claims there are more than 150 million active users.