Hi,

I just save setup NAT with two internet connections (fedora core 3):

eth2 is one internet connection, default gateway (let's say 1.2.3.4)

eth0 is another internet connection 5.6.7.8 with bunch of static routes (national ip pool) for this example let's say there is only one static route to 100.0.0.0/16

eth1 is lan 192.168.0.254 (192.168.0.0/24)

nat working fine, static route balance connections right as I which but problem is incomming connection (smtp for now or can be any other)

I have two mx records:
MX=1.2.3.4
MX=5.6.7.8

and :
-A PREROUTING -p tcp -m tcp --dport 25 -j DNAT --to-destination 192.168.0.28

when ip 7.7.7.7 connect to 1.2.3.4 all working fine but:
when ip 100.0.7.7 connect to 1.2.3.4 connection drop because (I supose) answer going to eth0 (5.6.7.8).

What I should do, why iptables didn't keep connection persists ?

Tnx in advance
Dejan

P.S. i'm newbie in linux world
P.P.S. sorry about that english :)