Mail will not send in HTML

Try this one.

  add_filter( 'wp_mail_content_type', 'wpdocs_set_html_mail_content_type' );

    $to = '[email protected]';
    $subject="The subject";
    $body = 'The email body content';
    $headers = array('Content-Type: text/html; charset=UTF-8');

    wp_mail( $to, $subject, $body , $headers);

    // Reset content-type to avoid conflicts -- https://core.trac.wordpress.org/ticket/23578
    remove_filter( 'wp_mail_content_type', 'wpdocs_set_html_mail_content_type' );

    function wpdocs_set_html_mail_content_type() {
        return 'text/html';
    }