sending mail with a script question

[David Banning]

I am running a php program in a browser which eventually
compiles some files and emails them to a person of their 
choosing. The problem is that the system identifies the
browser user as nobody.

I send the mail using a line something like;

cat textfile | mutt -s"Quote/Attachments" -afile1 -afile2 john at doe.com

but the problem is that the recipient sees the sender address as
from "nobody at ourhost.com", when I want it seen as "david at ourhost.com".
I have the name of the user available in the script but I see no
way of running the mail script as that person since any browser viewing
the system is "nobody".