I've migrated from a custom dovecot, procmail, fetchmail setup to Zimbra and have nearly everything set up as I want it. What I'm missing is the ability to filter out messages by target address, something procmail does with ^TO_. The problem is that the real target address can be in any of a number of header fields, depending on the delivery type (e.g. bcc, forwarded, etc).

procmail replaces ^TO_ by a regex that covers a dozen or so possible header fields, I'm looking for something similar in Zimbra, something that saves defining all the possible header fields as conditions.