If there is another way to go about this, I would be glad to hear it. I have been googling this one piece of the puzzle for most of the day.
I have outsourced spam filtering for a handful of accounts in the domain (I'll use example.com).
Anything coming in for email@example.com gets rewritten to firstname.lastname@example.org in the aliases file. mx2.example.com filters the mail and sends it back to email@example.com.
I currently have a procmail script:
| /usr/bin/sed -e 's/^To:/s/_filtered//'
This strips the _filtered off of firstname.lastname@example.org, so it gets delivered to email@example.com. No muss, no fuss. I was quite proud of myself when I figured out how to implement it.
Alas, that isn't going to fly with Zimbra. This is the last piece before I can migrate (I don't think spamassassin is going to be good enough filtering on its own for these 5 users). I know I could just try it without the external filtering, but if there is a problem I will need a quick implementation solution, so better to figure it out before hand.
Thank you for any suggestions.