This post originally appeared on the Netscape Blog.

Netscape is pleased to announce the availability of the first public alpha of Netscape Messenger 9, a mail and news client, to complement the Netscape Navigator Web browser. This release is now available for download from mailnews.netscape.com for Windows, Mac, and Linux.

The release notes for 9.0a1 are here; they include download and installation instructions.

NOTICE: This alpha release is an early developer milestone of the next major version of Messenger. It is being made available for testing purposes only. If you are currently using a previous Netscape mail client, you should not switch to Messenger 9a1 as your primary mail and news client. Feel free, however, to install and test it so that you can help shape the future of this product.

Report any bugs, or request any features, via this feedback form.

Netscape Messenger 9a1 is based on Thunderbird 2.0.0.9, giving it a secure and efficient base, as well as allowing it to support Thunderbird-compatible extensions. As we move through the alpha period with this product, we look forward to adding the most-requested features from the community, allowing us to improve on an already great product.

Along those lines, we have two questions for you:

1. What is the #1 killer feature that you’d like to see in the final release of Messenger 9?

2. Google and Yahoo have recently made announcements to the effect that they’ll be building social networking features into their webmail clients. Are you interested in seeing social features added to Messenger?