Контактная форма не отправляет сообщение

Моя контактная форма в php не отправляет сообщение на почту, поэтому мне нужно знать, в чем проблема. Здесь вы найдете html-форму с именем файла: index.php и форма php с именем: mail.php

<form class = "form" action = "mail.php" method = "post" name = "contactform">
    <input class = "name" type = "text" placeholder = "Name" name = "name">
    <input class = "email" type = "email" placeholder = "Email" name = "email" >
    <input class = "phone" type = "text" placeholder = "Phone No:" name = "phone">
    <textarea class = "message" id = "message" cols = "30" rows = "10" placeholder = "Message"name = "message"  ></textarea>
    <input class = "submit-btn" type = "submit" value = "Submit">
</form>

<?php
if (isset($_POST['submit']) ) {
    $name = $_POST['name'];
    $email = $_POST['email'];
    $phone = $_POST['phone'];
    $message = $_POST['message'];
    $from = 'From:  phone'; 
    $to = '[email protected]'; 
    $subject = 'message';

    $body = "From: $name\n E-Mail: $email\n Phone Number: $phone\n Message:\n $message";

    if (isset($_POST['submit'])) {
        if (mail ($to, $subject, $body, $from)) { 
            echo '<p>Your message has been submitted</p>';
        } else { 
            echo '<p>Something went wrong, please try again!</p>'; 
        }
    }
}
?>