Thunderbird 1.0.6 is a stability update. We recommend that users upgrade to this latest version.
To avoid crashes or other problems, do not install a new version using the installer into the same folder as an older zipped installation.
Here's what's new in Thunderbird 1.0.6:
Restore API compatibility for extensions that did not work in Thunderbird 1.0.5, including Enigmail.
Internet and communication
Windows, Linux, Mac OS X
Product page: here