[K12OSN] [OT] forcing mail traffic to mailgate

[Julius Szelagiewicz]

Dear Folks,
	a question a bit out of topic: How should I force outgoing mail
from widoze boxes on eth0 to go through my mailgate box instead throuh
whatever the little buggers have defined in the mail preferences.
	My problem stems from the fact that i am forced to allow people to
connect laptops to the network and i don't have the automated virus
scanning going yet. All my normal mail traffic goes through mail gate that
does spam and virus check *both* ways, but if the virus sends itself, it
can do it directly.
	I was thinking in terms of an iptables rule that would move all
the port 25 traffic from eth0 to the mailgate_address:25, thusly:

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 25 -j DNAT
--to-destination 216.216.171.236:25

Is this feasible, is this enough? tia, julius