signature file

SIGNATURE FILE

It is common practice in network mail to add what is called a "sig" or 
  "signature file" to the end of your outgoing messages.  Typical content
  is your name, title and organization, phone number, postal address, 
  electronic mail address, and so on, to identify yourself and make it
  easier for people to reach you.

Create the file with emacs (or any editor).  The file must have the name 
  .signature (notice the dot), and be in your home directory.  The usual
  etiquette is to keep it to 4 lines or less.

In MM, change the variable APPEND-SIGNATURE to either YES or ASK.  YES
  means append the sig to all outgoing mail, ASK means for MM to ask for
  each message whether to append it.  You will not see the sig when you
  use the DISPLAY command--it is appended during mailing.  

Type "help set append-signature" for more information on the variable.