9 Feb
2014
9 Feb
'14
5:43 p.m.
Here is what I'd do.
Only allow 44 net to talk to the mail host directly:
iptables -A INPUT -s ! 44.0.0.0/8 -p tcp --dport 25 -j DROP
Set a MX record and set up an exchanger for any external mail you need to deal with.