* @param $body String: email's text.
* @param $replyto MailAddress: optional reply-to email (default: null).
* @param $contentType String: optional custom Content-Type (default: text/plain; charset=UTF-8)
+ * @throws MWException
* @return Status object
*/
public static function send( $to, $from, $subject, $body, $replyto = null, $contentType = 'text/plain; charset=UTF-8' ) {