Miramar Alpha 3 is a preview release for the next major version of Thunderbird that is being built on top of the next generation of Mozilla's layout engine, Gecko 2.0. Miramar Alpha 3 is being made available for testing purposes only and is intended for developers and our testing community.
This release does not represent the final product. Some of the features listed below are highly experimental and will likely change before the final release. They may come with crashes and bugs and may potentially cause data loss in profiles (configuration data, preferences, downloaded mail).
Please do not use Miramar Alpha 3 in a production environment.