How to learn about email protocols like POP

I get many emails asking how I learn about protocols/applications and how to determine what is good and bad?

In this video I show you how I use a free email server (http://www.hmailserver.com), Mozilla’s portable version of Thunderbird’s email client and Wireshark to learn these protocols.

As I analyze the trace, I show you how to use Follow TCP Stream in combination with good old Telnet to reproduce what the application was doing.

In closing, I always encourage people to learn how to test a server using something other than ping, like sending some application commands. Some network monitoring tools will use this technique to measure response time.