frg, thanks for the offer in IRC to publicize the Thunderbird bug day. The blog post is at https://blog.mozilla.org/thunderbird/2019/04/all-bugs-fixed/
You can either copy the full text of that blogpost (Ryan could perhaps supply you with the source) or perhaps simpler and faster to use what's below and then reference the blog post link so people can read the full announcement.
All Thunderbird Bugs Have Been Fixed
We still have open bugs, but we’d like your help to close them!
We are grateful to have a very active set of users who generate a lot of bug reports and we are requesting your help in sorting them, an activity called bug triage. We’re holding “Bug Days” on <April 8th> (all day, EU and US timezones) and <April 13th> (EU and US timezones until 4pm EDT). During these bug days we will log on and work as a community to triage as many bugs as possible. With several of us working at the same time we can help each other in real time – answering questions, sharing ideas ideas, and enjoying being with like-minded people.
No coding or special skills are required, and you don’t need to be an expert or long term user of Thunderbird. Some things you’ll be doing if you participate:
Help other users by checking their bug reports to see if you can reproduce the behavior of their reported problem.
Get advice about your own bug report(s).
Learn the basics about Thunderbird troubleshooting and how to contribute.
Sorry for the joke! But we hope you’ll join us on the 8th or the 13th via #tb-qa on Mozilla’s IRC so that we can put these bugs in their place which helps make Thunderbird even better. If you have any questions feel free to email email@example.com.
Visit the <blog post> to see the full announcement.