from

FROM  -  replace the FROM field

Usage:  FROM [text]

The FROM command changes the FROM field of the current outgoing message.
  The FROM field is normally filled automatically with your name and
  electronic mail address.  You can substitute some other text either 
  by using the FROM command or by using SET DEFAULT-FROM.  MM will then
  add a REPLY-TO field containing your name and electronic mail address.  
  Unless the FROM field contains your own electronic mail address, MM will 
  also add a SENDER field during mailing, which is not visible when you 
  use DISPLAY to look at the message.

If you want to change the name part on all your outgoing mail, change the
  variable PERSONAL-NAME rather than DEFAULT-FROM.

If you want replies to go to someone else, leave the FROM field alone
  and use the REPLY-TO command to add an address for replies.

The FROM command with no text inserts your name and userid as in 
  /etc/passwd (the default).
     
Example:   
    Send>display headers
     From: Joseph Brennan <brennan@columbia.edu>
     To: fuat
     Subject: finishing up
    Send>from The Office Upstairs
    Send>display headers
     From: The Office Upstairs
     To: fuat
     Subject: finishing up
     Reply-To: Joseph Brennan <brennan@columbia.edu>

  Note that the SENDER header field does not appear although it will be
  added during mailing.  You can change or erase the REPLY-TO field if
  you want to.  

For more help, type "help" and one of these topics:
  display   reply-to   erase   set default-from   set personal-name   
  addressing   header-field   signature-file