php.ini & ini_set

I am working on a website for a friend that is being hosted by a third party
(which uses Linux) and I don't have access to the php.ini or any other
system files.

The problem I am having is this. When an email is sent from the website and
the user receives it, it says it is from nobody@hosting.com instead of the
websites email address. How can I get it to say it is coming from the
website address. I do have access to a cgi bin, and maybe .htaccess if
something can be done with these. I thought though that I could use ini_set
to do this.

Any thoughts.

Thanks