This would make them loads more useful.
Indeed, right now the the reason I want to create a list is to more easily be able to spot emails related to a Board I'm on (which currently I don't think they'll help with).
I use Cloudron with Gandi & Hetzner
You can set flags on the email with sieve filters. I think this is only available in roundcube UI though.
Then, in thunderbird, you can highlight them accordingly - https://support.mozilla.org/en-US/kb/message-tags