I built a fifteen-year career out of analyzing the spam in my own inbox.

First I learned how to real mail headers. Then, I learned how to use the Unix dig command. Then I learned traceroute and WHOIS. I learned how to search online for postal addresses and identify the postal drop boxes used by spammers.

The more spam I got, the better my skills at analyzing it became. I learned about open mail relays and how to test for them by logging in directly on port 25 and issuing commands by hand.