I have a PHP script on my website that sends emails using the basic mail() function — not SMTP or wp_mail() from WordPress. The email sends successfully to other addresses I own (like Gmail and Outlook), but emails sent to my Zoho-hosted address are never received — not even in the spam folder.

The sending address is no-reply@info.fake.com, which is a Bluehost-hosted subdomain email. Here's the exact PHP code I'm using to send the email:

<?php
// Send email using raw PHP mail()
function send_email_test() {
    $to = 'fake@fake.com'; // My Zoho address
    $subject = 'Email Test v2';
    $message = '<h2>v2 This is a test email</h2>
                <p>The email system is working properly.</p>
                <p><strong>Time:</strong> ' . date('Y-m-d H:i:s') . '</p>';

    $headers = "MIME-Version: 1.0" . "\r\n";
    $headers .= "Content-type: text/html; charset=UTF-8" . "\r\n";
    $headers .= "From: no-reply@info.fake.com" . "\r\n";
    $headers .= "Reply-To: no-reply@info.fake.com" . "\r\n";
    $headers .= "X-Mailer: PHP/" . phpversion();

    if (mail($to, $subject, $message, $headers)) {
        echo "Mail sent successfully.";
    } else {
        echo "Mail failed to send.";
    }
}
send_email_test();
?>

Emails sent using this code arrive everywhere except my Zoho mailbox (fake@fake.com). Can you help me determine why Zoho isn't accepting or delivering these?