The purpose of the mynetwork feature is to prevent clapf running spam check on emails coming from certain IP-addresses. Note that clapf still checks for viruses inside emails coming from “mynetwork”.

Let's say, your postfix box running clapf relays emails coming from your LAN (11.22.33.0/24), and you don't want clapf to run spam detection on these emails. All you have to do is to specify your LAN, eg.

mynetwork=11.22.33.

The mynetwork variable is a similar comma separated list like skipped_received_ips. The '$'-sign is available, too, see the following example:

mynetwork=84.15.1.8$

This will match on 84.15.1.8, but not on 84.15.1.80-84.15.1.89!

In case of postfix, enable the XFORWARD feature in /etc/postfix/main.cf:

lmtp_send_xforward_command = yes
smtp_send_xforward_command = yes
smtpd_authorized_xforward_hosts = 127.0.0.0/8