In this chapter we will cover some of the more common SMTP issues, including sending/receiving mail from the firewall, forwarding SMTP traffic to an internal mail server, and dealing with special circumstances to keep in mind when firewalling SMTP servers.
Can iptables/netfilter alert via e-mail?
Natively, no, it cannot. There are numerous ways to add in alerting capabilities with user space tools such as the IDS snort (http://www.snort.org).
Can firewall rules be used to route traffic based on the recipient?
The short answer is no. The (very) long answer is yes, but you would need to use something like iproute2 (ftp://ftp.inr.ac.ru/ip-routing/) or an application layer proxy. It is also possible to ...