Dissecting Email Headers, Part I

This is just to simple little guide. Nothing fancy, I'm not going to dig into all the MTA/SMTP and mail routing, just show you one example of the traces SMTP traffic leaves behind.

Have you ever wondered where you can find the source ip address in an email?
Here is a mini howto in dissecting mail headers.

In Gmail, you can open up the headers by "clicking" at the "More Options" in an opened email, and then
"Show original". This will open up a new browser window, with your email in pure 7-bit ascii.

Email Headers are like the front of an envelope or back of postcard.
The "stamps" are made by the involved SMTP servers, used in the transmission of the email.
The header show the stamps in the order from the bottom and up.

Working your way from the bottom (or middle) of the email header towards the top is the path taken to get from t
he source to the destination. Finding the source ip address is usually easy. Just find the field that says X-Ori
ginating-IP or something similar. It sometimes differs from mail servers. There is however a standard for this i
n RFC 822.