php submit form works only on localhost

Question

im new to PHP, and I created a page called contact.php and there is a simple contact-us form in it.

The form works successfully in localhost, but on the website it doesn't. The form itself looks good but I don't recieve any mail after i fill a form. What can be the reason? I don't know if this is matter but i placed the php before all of the html. you can see the form in this address: http://tevachocolate.myartsonline.com/contact.php

Here's the code: (I replaced my mail with *****)

PHP

    <?php
    
    if($_POST["submit"]) {
        $recipient="******@gmail.com";
        $subject="התקבל טופס מאתר ׳טבע השוקולד׳";
        $sender=$_POST["sender"];
        $senderEmail=$_POST["senderEmail"];
        $senderPhone=$_POST["senderPhone"];
        $message=$_POST["message"];
    
        $mailBody="שם: $sender\n אימייל: $senderEmail\n טלפון: $senderPhone\n\n הודעה:$message";
    
        mail($recipient, $subject, $mailBody, "From: justadress@mine.com");
    
        $thankYou="<p>תודה רבה! פנייתך התקבלה.</p>";
    }
    
    ?>

and the form:

HTML

  <form method="post" action="contact.php" class="tofes">
    <label>שם מלא:</label>
    <input name="sender">

    <label>כתובת אימייל:</label>
    <input name="senderEmail">

    <label>טלפון:</label>
    <input name="senderPhone">

    <label>הודעה:</label>
    <textarea rows="5" cols="20" name="message"></textarea>
<br>
    <input type="submit" name="submit" value="שליחה">
    <?=$thankYou ?>

</form>