Outlook Express

Open the message. Choose "File" from the options menu bar, then click "properties". Another window will open, showing two tabs. You want to choose the one titled "Details". Then cut and paste the headers into the message you want to forward.

Outlook

Double click on the message to open itup, click on "View --> Options", and you will see the message headers in a box at the bottom of the window. You can copy/paste them from that window.

Hotmail

Go into "Options", "Preferences", and choose "Message headers". You'll want to choose the "Full" option to display Received: headers. "Advanced" will display that as well as MIME headers. Do note, however, that sometimes Hotmail has to press some previous generation mailservers into service, and messages sent through those mailservers won't show any headers no matter what.

Eudora

Open the message. Under the title bar are four options. The second from the left is a box which says "Blah, Blah, Blah." Click on that to display the full headers.

Netscape Mail

Choose "OPTIONS" from the options menu bar. Listed as an option is "Show Headers". Choose full headers.

Elm, Pine, and Mutt

Press "h" from the message selection menu to view the full headers of the currently selected message.

Pegasus

Choose "READER" from the options menu bar. Listed as an option is: "Show all Headers". This does not work for HTML messages, however. A workaround is to select the message properties, and de-selecting "Contains HTML data".