Email Security Sniffers

A "sniffer" is a sofware program that runs on a computer in a network and looks for specific words and phrases in the data that flows through it. Hackers sometimes use them to spy on people by looking for email addressed to certain people or mentioning certain subjects. Firewalls also use sniffers as internet filters to look for information. For example, you could instruct the firewall to block any packet with the word "X-rated" in it. The only catch is that it has to be an exact match. The "X-rated" porn filter would not catch "X rated" (no hyphen). But you can include as many words, phrases and variations of them as you need.