Every e-mail message is made up of its body (the message) and its headers. The headers are initially generated by the software that is used to write the message (e.g. Eudora, Outlook, etc.), and each machine that handles the mail will usually add its own headers in addition.
Message headers are often essential to determine why your mail isn't working; or to enable us to block spam, and we may ask you to send them to us.
How do I get them?
Thunderbird and Mozilla Mail
Now full headers should be viewable when you go into an email and will be included when you forward or reply to an email.
After you are finished you may want to go back into:
and return the setting to Normal
Outlook Express for Macintosh