Simple mail trick for good or evil

My mail client (Mail.app) allows me to configure which email headers get displayed. I set it up to display some extra headers for my own novelty...

X-Mailer: display the Mail client program used to craft a given email. This is mostly for my own curiosity. If somebody is using a Mac, I might ask them if they're upgrading to OS X Tiger. If they're using Outlook, I'll think twice about opening the screensaver attachments!

X-Originating-Ip: this header appears in Hotmail.com messages. It gives the IP address of the sending user. I can use this to probe for FTP servers, SSH servers and the like on my friend's machines. For non-hotmail users, this IP address is usually found in the last of the Received: headers.

# posted by Jesse Wilson on Monday, February 21, 2005