How can PHP be utilized effectively for sending newsletters or notifications on a website?

To send newsletters or notifications on a website using PHP, you can utilize the `mail()` function in PHP to send emails to your subscribers. You can create a PHP script that fetches the list of subscribers from your database and sends personalized emails to each subscriber. Make sure to include proper headers and content in your email to avoid being marked as spam.

<?php
// Fetch subscribers from database
$subscribers = array('subscriber1@example.com', 'subscriber2@example.com');

// Loop through subscribers and send personalized emails
foreach($subscribers as $subscriber){
    $to = $subscriber;
    $subject = 'Newsletter Notification';
    $message = 'Hello, this is a newsletter notification.';
    $headers = 'From: yourwebsite@example.com' . "\r\n" .
        'Reply-To: yourwebsite@example.com' . "\r\n" .
        'X-Mailer: PHP/' . phpversion();

    // Send email
    mail($to, $subject, $message, $headers);
}
?>