How can I automate the process of sending HTML newsletters in PHP?

To automate the process of sending HTML newsletters in PHP, you can use a combination of PHP's mail function and a loop to send the newsletter to a list of subscribers. You can also use PHP's built-in mail libraries or third-party services like Mailchimp to handle the sending process more efficiently.

<?php
$newsletter = "<html><body><h1>Welcome to our Newsletter!</h1><p>This is some sample content for our newsletter.</p></body></html>";
$subscriberList = array('subscriber1@example.com', 'subscriber2@example.com', 'subscriber3@example.com');

$subject = 'Your Weekly Newsletter';
$headers = "MIME-Version: 1.0\r\n";
$headers .= "Content-type: text/html; charset=iso-8859-1\r\n";

foreach ($subscriberList as $subscriber) {
    mail($subscriber, $subject, $newsletter, $headers);
    echo "Newsletter sent to: " . $subscriber . "<br>";
}
?>