Dovecot sieve - How to check which username a mail is being delivered to?

[Yannik Sembritzki]

Hi everyone,

I am looking for a way to check which mailbox an email is being
delivered to in a global sieve filter.

After not being able to find some kind of variable that is populated by
dovecot automatically, I tried to use the `Delivered-To` header.
I tried a check like this:

    header :is "delivered-to" "<user at domain.org>"

Unfortunately, this does not only match the first occurence of the
header (which can be assumed is added by dovecot), but any occurence of
this header in the email, which could be added due to previous
deliveries and forwards, or just cause of malice.

Is there any way to achieve this?

Best regards,
Yannik