#!/bin/bash
LOCALNET=192.168.1.0/24
for MAILSERVER in 87.250.251.37 87.250.251.37 ... ; do
        iptables -A FORWARD -p tcp -s $LOCALNET -d $MAILSERVER --dport 25 -j ACCEPT
        iptables -A FORWARD -p tcp -s $MAILSERVER -d $LOCALNET --sport 25 -j ACCEPT
        iptables -A FORWARD -p tcp -s $LOCALNET -d MAILSERVER --dport 110 -j ACCEPT
        iptables -A FORWARD -p tcp -s MAILSERVER -d $LOCALNET --sport 110 -j ACCEPT

        iptables -t nat -A POSTROUTING -p tcp -s $LOCALNET --dport 110 -j MASQUERADE
        iptables -t nat -A POSTROUTING -p tcp -s $LOCALNET --dport 25 -j MASQUERADE
done