3 NIC & 2 public IP

Hello,
OS is Debian. I've got 2 pblic IP from 2 ISP & 1 LAN(eth0 - LAN, eth2 -
ISP1, eth2 - ISP2).
I want to configure this server to route LAN thru eth1.
eth2 should be use to send/receive e-mails and www/webmail.
How should I configoure this server to do what I want?
Now works fine until eth2 is down. When I change state to up server
sends ping outside, but dont respond on pings send from outside.
NIC config:
iface eth0 inet static
address 192.168.1.2
netmask 255.255.255.0
network 192.168.1.0
brodcast 192.168.1.255
iface eth1 inet static
address 212.160.x.157
netmask 255.255.255.224
network 212.160.x.128
broadcast 212.160.x.191
gateway 212.160.x.129
iface eth2 inet static
address 83.15.y.43
netmask 255.255.255.248
network 83.15.y.40
broadcast 83.15.y.47

Sorry for my English!

> How should I configoure this server to do what I want?

i'm not sure if i understand what u want but i guess the answer is:

iproute2, policy based routing

> Now works fine until eth2 is down. When I change state to up server
> sends ping outside, but dont respond on pings send from outside.

which ip do you ping? from which subnet? how does your routing table look
like? i think the icmp-echo-reply packages are routed through eth2 while
you ping eth1 from outside.