title: The PHP contact form is not working
body: <p>I'm trying to send filled HTML form by PHP. Actually, it doesn't show any errors but email is not be sent.</p>
  
  <pre><code>&lt;?php 
  if(isset($_POST['submit'])){
      $to = "viva7real@yandex.ru"; //my Email
      $from = $_POST['email']; // sender's email
      $first_name = $_POST['first_name'];
      $last_name = $_POST['last_name'];
      $subject = "Form submission";
      $subject2 = "Copy of your form submission";
      $message = $first_name . " " . $last_name . " wrote the following:" . "\n\n" . $_POST['message'];
      $message2 = "Here is a copy of your message " . $first_name . "\n\n" . $_POST['message'];
  
      $headers = "From:" . $from;
      $headers2 = "From:" . $to;
      mail($to,$subject,$message,$headers);
      mail($from,$subject2,$message2,$headers2);
      echo "Mail Sent. Thank you " . $first_name . ", we will contact you shortly.";
      }
  ?&gt;
  
  &lt;!DOCTYPE html&gt;
  &lt;head&gt;
  &lt;title&gt;Form submission&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
  
  &lt;form action="" method="post"&gt;
  First Name: &lt;input type="text" name="first_name"&gt;&lt;br&gt;
  Last Name: &lt;input type="text" name="last_name"&gt;&lt;br&gt;
  Email: &lt;input type="text" name="email"&gt;&lt;br&gt;
  Message:&lt;br&gt;&lt;textarea rows="5" name="message" cols="30"&gt;&lt;/textarea&gt;&lt;br&gt;
  &lt;input type="submit" name="submit" value="Submit"&gt;
  &lt;/form&gt;
  
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Is there any bugs or mistakes in the code?</p>