Postfix and multiple IP's

Hi.

I have a server with 3 real IP addresses:

Code:

auto venet0:0
iface venet0:0 inet static
        address IP1
        netmask 255.255.255.255
        broadcast 0.0.0.0
auto venet0:1
iface venet0:1 inet static
        address IP2
        netmask 255.255.255.255
        broadcast 0.0.0.0
auto venet0:2
iface venet0:2 inet static
        address IP3
        netmask 255.255.255.255
        broadcast 0.0.0.0

I want postfix to use IP2 for sending emails, and NOT IP1.

Is there a way to do this?

Thanks.