Learning Sieve
 

So far Fastmail's rules did everything I needed.
It seems that now I'll have to start using Sieve.
Where can I (complete beginner) learn Sieve (at least it's basics)?
Thanks for any info.

Try How-To: Write simple sieve scripts

Thank you janusz.
Much appreciated ;)

I don't profess to know much about Sieve, but this looks like extensive information from ProtonMail:

https://protonmail.com/support/knowl...ustom-filters/