Problems with e-mail delivery

[delirila]

I know there are a few of these topics out there, but none of the conclusions for those worked for me.

I'm having a few problems with the delivery of e-mails on my site.

I have a PHP script that takes form input and sends it as an e-mail to me; however, when I submit it, it doesn't go through. I have an echo tell me whether or not the message was sent, and it always fails.

Also, I cannot send e-mail from the RoundCube client that cPanel comes with. I can receive e-mail to it, but any messages sent from it do not go through.

Here's my PHP:

<?php
 $to = "my@email.com"; // Hidden
 $subject = "Test Subject";
 $body = "Test body message.";
 $headers = "From: admin@deliriumla.x10.mx\r\n";
 $headers .= "Reply-To: admin@deliriumla.x10.mx\r\n";

 if (mail($to, $subject, $body, $headers)) {
   echo("<p>Message sent</p>");
  } else {
   echo("<p>Message not sent</p>");
  }
?>

Any help would be appreciated.