add_label

$folder->add_label(msg_num, label)

• Associates the label label with the message msg_num. Returns on success or if the label has a length of 0. Possible values of label are:
  • deleted
  • Used by delete_message and sync to process message deletion.
  • edited
  • Added by update_message to indicate that the message has been edited.
  • filed, forwarded, printed, replied
  • Not acted on.
  • seen
  • Message has been viewed by the user. Set by get_message for any message it has retrieved.