WooCommerce Email Blacklist

/**
 * Snippet Name:     WooCommerce Email Blacklist
 * Snippet Author:   coding-bunny.com
 * Description:      Prevents orders from specific email addresses or domains in WooCommerce checkout.
 * Version:          1.0.0
 */

add_action( 'woocommerce_after_checkout_validation', 'cbweb_blacklist_email_and_domain', 9999, 2 );

function cbweb_blacklist_email_and_domain( $data, $errors ) {
    $blacklisted_emails = cbweb_get_blacklisted_emails();
    $blacklisted_domains = cbweb_get_blacklisted_domains();

    $billing_email = isset( $data['billing_email'] ) ? sanitize_email( $data['billing_email'] ) : '';

    if ( ! empty( $billing_email ) ) {
        $billing_email_lc = strtolower( $billing_email );
        $email_domain     = cbblc_extract_email_domain( $billing_email_lc );

        if ( in_array( $billing_email_lc, $blacklisted_emails, true ) || in_array( $email_domain, $blacklisted_domains, true ) ) {
            $errors->add(
                'blacklist_email_error',
                __( 'Sorry, our website is currently unable to process your request.', 'cbweb' )
            );
        }
    }
}

/* EMAIL BLACKLIST */
function cbweb_get_blacklisted_emails() {
    return array_map( 'strtolower', [
        'example1@gmail.com',
        'example2@lorem.io',
        'example3@john.co',
    ]);
}

/* DOMAIN BLACKLIST */
function cbweb_get_blacklisted_domains() {
    return array_map( 'strtolower', [
        'example1.com',
        'example2.org',
        'example3.com',
    ]);
}

function cbweb_extract_email_domain( $email ) {
    $at_pos = strrpos( $email, '@' );
    if ( false === $at_pos ) {
        return '';
    }
    return substr( $email, $at_pos + 1 );
}