Also, mail scripts should NEVER accept just any recipient! If you want to pass the From address to the script make sure you check it against a list of valid recipients on the server side.
There's an "improved formmail" script at the NMS scripts archive which should be easy enough to configure to your needs. If you want just the mailing code, try Mail::Send.
Here is some misunderstanding, it seems.
Hosting service support Sendmail. Its location is