Thunderbird - the email client from Mozilla is about to have version 24 reach the beta channel. Thunderbird has been running version 17.0.x since November 2012. It’s been a year of core development that we are about to catch up , this means changes in the networking layer, the javascript engine, gecko. It also means that all the changes (over 600) we made in Thunderbird code need to be tested. Depending on who you are it’s going to matter differently.

If you are a user, you’ll want to enjoy the same feature set, the same extensions and the same comfort for reading email, newsgroups and RSS feeds. To make sure we didn’t break important features that matter to you, switch today to the beta[1] and report issues to us. Also we’ll have a testday/testweek[2] come and participate and help make Thunderbird just better.

You are an extension developer - your extension works great in Thunderbird 17. It’s now time to try the beta series[1] and see if your extension still works in version 24, if not time to fix it and submit it to AMO. We’ll probably be able to help you in #maildev on irc.mozilla.org.

You are an IT administrator and are using Thunderbird in your corporate network - make sure major things don’t break before 24 comes out. For Those wondering Thunderbird ESR[3] is currently exactly what Thunderbird 17.x is except for the update mechanism, we don’t differ by a patch on both branches. So testing 24 is the right way to go.



You are an integrator and use Thunderbird as your mail client in your solution (say OpenXchange or Blue-mind) - well now is the time to figure out if the next major version of Thunderbird is still working the way you are used to.

I know that currently the beta version available for download is version 23 - but that will change to 24 soon - and in most cases running the version for more than a few hours is way more useful, so running 23 nos is the way to go.

For those wondering why I’m asking for more beta usage I’m going to give you some “stats”, they aren’t precise or anything but it’s numbers and they still mean things we have roughly 8 Million daily users, and around 35 Thousand beta users, that’s 0.43%. It’s too low and has bitten us in the past when we discover that for example a major AV vendor doesn’t work with latest release and that it affects 10% of our users, just because none of our beta testers were using it.

Ludovic - for the Thunderbird Quality team.

[1] available at https://www.mozilla.org/en-US/thunderbird/all-beta.html .

[2] To be announce a bit later , probably here or on the various Thunderbird mailing lists .

[3] see https://wiki.mozilla.org/Thunderbird/Enterprise .