Sieve filters support

[emersion]

https://tools.ietf.org/html/rfc5228

[foxcpp]

Having ManageSieve protocol too would be nice: https://tools.ietf.org/html/rfc5804

Also, found Sieve lang parser for golang: https://github.com/qingshan/sieve. I wonder if it works...

[emersion]

Once sieve filtering has been added, is the possibility of having a kitteh+junk@kitteh.pw email that gets emails forwarded into spam folder a reality?

Yes.

[helmut72]

Sieve support would be cool. Can't imagine any Imap service without Sieve.

[andris9]

When building WildDuck Mail Server we decided to not use Sieve and instead went with custom filtering system that is applied to incoming emails and is easy to integrate with a web UI. Basically these are If-This-Then-That rules (example). Such filters cover 90% of use cases required by users.

We did not see any value in actual Sieve mostly because it's a separate programming language (so there might be some security issues if a user is able to come up with a complex enough script). Also most users are not able to write it anyway, so usually it ends up being disguised by the UI into simpler forms.

[emersion]

Sieve has a great upside: it's a standard. So it really helps users switching from an email server to another without having to learn a new filtering DSL and convert all of their filters.

[emersion]

Additionally, Sieve is not Turing-complete (no loops, no functions), so I wouldn't be too worried about complex scripts.