Check out this video from SciShow which goes some way to explaining how an email gets from your computer to another.

Emails get routed through a series of computers to reach it’s destination.  It’s not a direct connection from your computer to another. That’s important to all email users because it means:

Privacy  –  any of those computers can make a copy of your message (unless it’s encrypted).  That copy can go to a hacker, criminal, the company running the computer or a government.  Just one reason why you should NEVER put a password, credit card or other personal details in a plain text email.

Spam filtering – emails go through one or more spam filters before reaching the destination.  The video mentions the difficulties in figuring out if a message is spam or not. It doesn’t mention the problem of genuine messages being wrongly stopped as spam.

The video talks about email message headers, we’ve talked about a nifty tool to analyze an email header.

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