Why is PHP's mail() sending me dozens of blank emails? - php

Question

I'm using PHP's mail() function within a WordPress theme to send form submissions to my email.
However, mail() has automatically sent me at least 20 blank emails,
within the last five minutes, without being submitted.
Could someone shed some light on what I've done to create this situation?
Here is the code from my (functions.php file)
function send_my_form(){
$form = array();
$form['fstname'] = $_POST['fstname'];
$form['lstname'] = $_POST['lstname'];
$form['email'] = $_POST['email'];
$form['message'] = $_POST['message'];
$send_to = 'fakeemail#gmail.com';
$subject = 'You\'ve recieved an email from' . $form['fstname'] . $form['fstname'];
$return = "-f" . $send_to;
$message = "First Name: " . $form['fstname'] . "\r\n";
$message .= "Last Name: " . $form['lstname'] . "\r\n";
$message .= "Email: " . $form['email'] . "\r\n";
$message .= "Message: " . $form['message'] . "\r\n";
$headers = 'MIME-Version: 1.0' . '\r\n';
$headers .= 'Content-type: text/html; charset=iso-8859-1' . '\r\n';
$headers .= 'From: ' . $send_to . '\r\n';
$headers .= 'Reply-To: ' . $form['email'] . '\r\n';
$headers .= 'Return-Path: ' . $send_to . '\r\n';
$headers .= '\r\nX-Mailer: PHP/' . phpversion();
mail($send_to, $subject, $message, $headers, $return);
}
add_action('wp_head', 'send_my_form');

Answer 1

This is what I mean by running it in a conditional. Verify the fields are set before running the mail script.
function send_my_form(){
if(isset($_POST['fstname']) && isset($_POST['lstname']) && isset($_POST['email']) && isset($_POST['message']))
{
$form = array();
$form['fstname'] = $_POST['fstname'];
$form['lstname'] = $_POST['lstname'];
$form['email'] = $_POST['email'];
$form['message'] = $_POST['message'];
$send_to = 'fakeemail#gmail.com';
$subject = 'You\'ve recieved an email from' . $form['fstname'] . $form['fstname'];
$return = "-f" . $send_to;
$message = "First Name: " . $form['fstname'] . "\r\n";
$message .= "Last Name: " . $form['lstname'] . "\r\n";
$message .= "Email: " . $form['email'] . "\r\n";
$message .= "Message: " . $form['message'] . "\r\n";
$headers = 'MIME-Version: 1.0' . '\r\n';
$headers .= 'Content-type: text/html; charset=iso-8859-1' . '\r\n';
$headers .= 'From: ' . $send_to . '\r\n';
$headers .= 'Reply-To: ' . $form['email'] . '\r\n';
$headers .= 'Return-Path: ' . $send_to . '\r\n';
$headers .= '\r\nX-Mailer: PHP/' . phpversion();
mail($send_to, $subject, $message, $headers, $return);
}
}