Why is "supernova" looking like outlook? NO, it does not. the "supernova" mockup is available in the nightly (daily) builds. although its not ready and has 4 month to get final, thunderbird looks very similar to the current design and behaves like that. this just a simple view from me, i dont use thunderbird for my daily mail.
I'm very happy with Thunderbird as it is now. Hope he doesn't get ruined. New doesn't always mean better.
i think they wont change a lot. the problem you name is that using an outdated mailer (or browser) is always a security risk. Lately i read about someone want to use TB v52 on windows 10. https://www.mozilla.org/en-US/security/known-vulnerabilities/thunderbird/ red means "high vulnerable" latest v52 is from jul'18 https://www.thunderbird.net/en-US/thunderbird/releases/ count cve https://www.cvedetails.com/product/3678/Mozilla-Thunderbird.html?vendor_id=452 some cve are not public due the risk to be used. an early preview to supernova https://developer.thunderbird.net/planning/roadmap mails are confidental, and a good prepped mail can harm that bad while opening or already in header.
