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

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@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