I am using the following script to send E-Mail via a web script as I am designing a legacy application which has no socket connection to be able to E-Mail out, and the only way I can do it is via a web script. It just needs to be a simple quick script with fields like: To, From (Name), Subject, Message.
I have tried the following code I found on the net but kept getting an "Invalid email address" and when editing the section out that checks email address in the script I was getting a 500 internal server error.
I have attached the code below but if anyone has a better one or can tell me how to fix my one I would appreciate it. I have also included the logs from Abyss when both the above errors occur
Mail Script constists of mail.html and mail.php
mail.html:

<html>
<head><title>Mail sender</title></head>
<body>
<form action="mail.php" method="POST">
<b>Email</b><br>
<input type="text" name="email" size=40>
<p><b>Subject</b><br>
<input type="text" name="subject" size=40>
<p><b>Message</b><br>
<textarea cols=40 rows=10 name="message"></textarea>
<p><input type="submit" value=" Send ">
</form>
</body>
</html>

mail.php:

<html>
<head><title>PHP Mail Sender</title></head>
<body>
<?php

/* All form fields are automatically passed to the PHP script through the array $HTTP_POST_VARS. */
$email = $HTTP_POST_VARS['email'];
$subject = $HTTP_POST_VARS['subject'];
$message = $HTTP_POST_VARS['message'];

/* PHP form validation: the script checks that the Email field contains a valid email address and the Subject field isn't empty. preg_match performs a regular expression match. It's a very powerful PHP function to validate form fields and other strings - see PHP manual for details. */
if (!preg_match("/\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*/", $email)) {
  echo "<h4>Invalid email address</h4>";
  echo "<a href='javascript:history.back(1);'>Back</a>";
} elseif ($subject == "") {
  echo "<h4>No subject</h4>";
  echo "<a href='javascript:history.back(1);'>Back</a>";
}

/* Sends the mail and outputs the "Thank you" string if the mail is successfully sent, or the error string otherwise. */
elseif (mail($email,$subject,$message)) {
  echo "<h4>Thank you for sending email</h4>";
} else {
  echo "<h4>Can't send email to $email</h4>";
}
?>
</body>
</html>

Abyss error log:

18/Mar/2008:22:19:14 +1100	SUID: 0	PUID: 0	RUID: 0	URI: 	Reading 0 bytes failed = The process cannot access the file because it is being used by another process.
18/Mar/2008:22:19:14 +1100	SUID: 0	PUID: 0	RUID: 0	URI: 	timeout-header2!
PHP Notice:  Undefined variable: HTTP_POST_VARS in C:\Abyss Web Server\htdocs\test\mail.php on line 7
PHP Notice:  Undefined variable: HTTP_POST_VARS in C:\Abyss Web Server\htdocs\test\mail.php on line 8
PHP Notice:  Undefined variable: HTTP_POST_VARS in C:\Abyss Web Server\htdocs\test\mail.php on line 9

---After removing validation---

PHP Parse error:  syntax error, unexpected T_ELSEIF in C:\Abyss Web Server\htdocs\test\mail.php on line 12