eskander wrote in php

i'm at a loss
i'm hosting a site off my server, i have an email script using php
people fill out a form and hit send and the php should do the rest
i know for a fact it used to work
i'm running mac os x server 10.3.6

the code i'm using is (god i hope this displays properly...)

mail($to, $subject, $message, "From: $username") or print "Could not send mail!";


all the variables do get filled, i'm sure of that
i believe the command is right but nothing is being sent
what's going on?