/* Simple recipient, one address */
$to_plugin = $to;
$to_name = (($to_name == null || $to_name == $to) ? '' : self::mimeEncode($to_name));
$to_list->addTo($to, $to_name);
Por esto:
/* Simple recipient, one address */
$to_plugin = $to;
//$to_name = (($to_name == null || $to_name == $to) ? '' : self::mimeEncode($to_name));
//$to_list->addTo($to, $to_name);
$to_list->addTo($to, $to_name);
O bien por esto:
/* Simple recipient, one address */
$to_plugin = $to;
$to_name = (($to_name == null || $to_name == $to) ? '' : self::mimeEncode($to_name));
//$to_list->addTo($to, $to_name);
$to_list->addTo($to);