Reference: add_label

add_label

 $folder->add_label(msg_num, label)

Associates the label label with the message msg_num. Returns 1 on success or 0 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.