Java EE (Java Enterprise Edition) General Discussion

Hi,everybody,
After i read mail i,i want to set my message is SEEN..
like this code:
msg.setFlag(Flags.Flag.SEEN, true);
msg.saveChanges();
fdInbox.close(true);
store.close();
but it's can't work.
on this line:: msg.saveChanges();
get a exception:POP3 messages are read-only
Anyone can tell me why and how to solve?

best regards

Alex