#Thunderbird had once mentioned they were working on it. But you have to remember, @thunderbird is just an email client, not an email provider. It is primarily your email provider that should be filtering spam. If it is too much, that means your email has been compromised and it is time for a new email account. That being said, the spam folder for Thunderbird on my system still works, but it is modeled after behavior, not general emails you may be getting. If you are getting to much spam that likely means some online business you provided your email to was compromised and they never told you.

It's the email for my domain name, it'll always get spam. Just need a reasonable filter.

Thunderbird's spam filter seems to be ...nothing, since stuff spoofing my DKIM and SPIF'd domain goes right through to my inbox. Used to Google, which even lets you see "yep this is probably compromised" on the headers. Trying to get as much off google as I can tho

We've got a guide to our spam filter in a blog post from last year. The adaptive filter uses a Bayes algorithm which need help in the form of 'spam'/'not spam' input to get it working well: https://blog.thunderbird.net/2024/09/thunderbird-and-spam/

We really hope this helps - and the blog also shows you how to set up external junk filters.