Well i am not using email verification so i am facing problem in checking correct form of email address

suppose if user enter support or support@ it accept it as well.

So i atleast want them to enter there email or at least they enter email form correctly

Here is my code:

   <?php
    require_once 'global.php';
    if (!isset($_SESSION['logged_in'])) {
        header("Location: login.php");
    }
    $user    = unserialize($_SESSION['user']);
    $email   = $user->email;
    $message = "";
    if (isset($_POST['submit-settings'])) {
        $email       = $_POST['email'];
        $user->email = $email;
        $user->save();
        $msg = "Done!<br/>";
    }
    ?>