TIL: Sieve (mail filtering language)

I use Fastmail for my emails, and today I found that you can set a custom mail filtering rule using language called Sieve.

Apparently there is also a protocol to manage Sieve script, but Fastmail doesn't support it :( I thought of writing a Just script or a Terraform provider, but too bad.

However: Fastmail supports JMAP API (!) so if I really wanted to, I can use SieveScript/set - but I'm too lazy. JMAP is crazytown.

Side note, Fastmail is awesome. Highly recommend.