The fourth field is actually the headers field. It does contain the from header. It does say in the manual that it is optional but some things are less optional than other. I have not managed to make mail work without the fourth field.
try setting you email up like.
/ recipients /
$recipient .= "Mary <mary@u.college.edu>" . ", " ; //note the comma
$recipient .= "Kelly <kelly@u.college.edu>" . ", ";
$recipient .= "ronabop@php.net";
/ subject /
$subject = "Birthday Reminders for August";
/ message /
$message .= "The following email includes a formatted ASCII table\n";
$message .= "Day \t\tMonth \t\tYear\n";
$message .= "3rd \t\tAug \t\t1970\n";
$message .= "17rd\t\tAug \t\t1973\n";
/ you can add a stock signature /
$message .= "--\r\n"; //Signature delimiter
$message .= "Birthday reminder copylefted by public domain";
/ additional header pieces for errors, From cc's, bcc's, etc /
$headers .= "From: Birthday Reminder <birthday@php.net>\n";
$headers .= "X-Sender: <birthday@php.net>\n";
$headers .= "X-Mailer: PHP\n"; // mailer
$headers .= "X-Priority: 1\n"; // Urgent message!
$headers .= "Return-Path: <birthday@php.net>\n"; // Return path for errors
/ If you want to send html mail, uncomment the following line /
// $headers .= "Content-Type: text/html; charset=iso-8859-1\n"; // Mime type
$headers .= "cc:birthdayarchive@php.net\n"; // CC to
$headers .= "bcc:birthdaycheck@php.net, birthdaygifts@php.net\n"; // BCCs to
/ and now mail it /
mail($recipient, $subject, $message, $headers);
straight out of the manual but it does work.
Mark.