在电子邮件中显示表单提交的页面

I have a html form on every page and I need to be able to show in the receiver email from which page the visitor submitted the form. How can I achieve this in PHP? I have tried using $_SERVER['REQUEST_URI'] whatsoever, but it just simply doesn't output anything. I'm using Wordpress.

<?php
  global $post;
  $post_slug=$post->post_name;
  $name = $_POST['firstname'];
  $email = $_POST['email'];
  $message="$name.$email";
    mail('example@gmail.com', "Hello", "$name 
 $email 
 $_SERVER['REQUEST_URI']");
    echo "works";
?>

Your code is fine except, you should enclose array variables inside strings with curled braces {}:

mail('example@gmail.com', "Hello", "$name 
 $email 
 {$_SERVER['REQUEST_URI']}");

If you check the official php documentation on: http://php.net/manual/en/language.types.string.php#language.types.string.parsing you can see in section "Complex (curly) syntax":

// Works, quoted keys only work using the curly brace syntax
echo "This works: {$arr['key']}";

you can get the actual url with :

$actual_link = "http(s)://$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";

You can try something this . Pass the title of your page ( or the permalink ) to a hidden html input and take the values as :

 $titlePage = get_the_title($post->ID);

 <input type="hidden" value="<?php echo $titlePage; ?>" name="pagetitle">

Then in your email code :

 $pagetitle = $_POST['pagetitle'];

Now you have your parameter, use it in your email like you want.