exclude network in prerouting

his is probably a very noob question

i have 3 outgoing connections 2 pppoe 1 VPN (they not really do balancing .. since it turned out to be not working really well)
so i use mangle/preroute to mark the packets i want to have routed trough the alternate gateway

the problem is this rules do also match for the local outgoing VPN connections and other private networks.

could maybe someone advice me in how to change this:

chain=prerouting action=mark-routing new-routing-mark=Out_133 passthrough=yes src-address=172.16.67.169 dst-address=0.0.0.0/0

to work with a exeption .. like the VPN networks and other private networks ?

oh while at the topic … what is “passthrough” for ?

If passthrough is not selected any remaining (i.e. lower) mangle rules will not be executed.