You can go grab it on AMO or wait for Thunderbird to tell you to update. This contains a one-line work around that makes the add-on work after the semi-recent change in the API. You can read all the fun details over in bug 586032.
You can get it over at AMO. This version includes the integration of Thunzilla, an add-on originally created by Justin Dolske. I also made some minor improvements on the detection algorithm for what e-mails you can reply to.
Version 0.3 of the Bugzilla Helper Add-on for Thunderbird has been released! Current users will have to update manually since sandboxed add-ons do not automatically update. New in this version:
Found a bug? E-mail me or leave a comment.
I just uploaded Bugzilla Helper 0.2.0. This improves on the last release by making making the submission of comments an asynchronous operation. It also uses the activity manager in Thunderbird to track the process of the submission, and retry it if an error occurs.
There are still some apparent issues with the REST API that the add-on is using, and I’ll likely include some workaround in upcoming versions. 0.2.0 is available on addons.mozilla.org and is a recommended upgrade. Current users will have to update since sandboxed add-ons do not automatically update.