Using blacklist_to method

[tirgil]

Hi,
I use Zimbra 8.0.2_GA_556
I use blacklist_from method in for custom blacklist. I edit this file /opt/zimbra/conf/spamassassin/local.cf and write rules as below
blacklist_from *@*toplu*

blacklist_from *@mrom2.com
It works perfectly. Now i try to set blacklist_to method. I don't know that there is a method like this. For example
blacklist_to groupname@yahoogroups.com
I want to block some groups mail. I have to use "to" section in email, because i don't want to block users.
How can i do it?
Thanks