Thank you frankman for the solution above.
Just wanted to let everyone know how this can be done with Zimbra 6.0.6+
All commands below is run as the zimbra user
Edit /opt/zimbra/conf/postfix_recipient_restrictions.cf and add this just before the permit line:
Code:
check_recipient_access hash:/opt/zimbra/conf/blacklist_clients
I make no guarantee that this will stick. Zimbra will probably just replace this one if you make changes in your zimbra admin gui. If someone know a better place to put this line, post a reply.
Then create /opt/zimbra/conf/blacklist_clients and put every address you want to block on it's own row. If you want the sender to know about your block, use REJECT. If not, use DISCARD.
Code:
libtorrent@mydomain.com DISCARD
registerflywhois@mydomain.com REJECT
Finally run postmap:
Code:
postmap /opt/zimbra/conf/blacklist_clients
Oh, you probably need to do a "postfix reload" after you have edited postfix_recipient_restrictions.cf.