Firstly, I am trying to setup zimbra using two machines. One will handle the spam/virus filter then deliver the filtered mail to another zimbra machine running the mailbox and ldap services. I noticed that on the spam filter machine, the amavisd.conf.in file contains
hostname => '@@zimbra_server_hostname@@',

which I had to change it to the line below in order to get the filter machine to use the ldap server running on the mailbox machine for amavisd.

hostname => '@@ldap_host@@',

When I installed zimbra on the filter machine, I told it to not setup ldap service and gave it the address of the second server as the ldap host. Apparently, that change was not applied to the amavisd.conf.in file. So I am wondering if I did something wrong or this might be a bug in zimbra installation script.

Secondly, how do I set up the filter machine to deliver processed messages to the zimbra server containing the mail stores?