Can you post a sample script?

Do you run PHP on Windows (using SMTP) or do you run it on Unix or Linux (using sendmail or equivalent)?

Also, can you post your configure line (if you're not on Windows)?

=======User input=======
The script I am testing:

<?
$recipient = "webmaster@test.com";
$subject = "Subject";
$message = "Message";
$header = "From: test@test.com";

mail($recipient, $subject, $message, $header);

?>

I am running this on Windows using smtp.
========================

What email address in php.ini are you referring to?
Please include these lines from your php.ini:

sendmail_from 
sendmail_path

No feedback. Closing.