how to delete message from POP3 server--using D7/indy10.0.52

Maybe i've got this all wrong, but i thought when you do pop3.delete and
then disconnnect, the selected msg is meant to be deleted? Here's the code i
use to delete msg:

procedure TForm1.deleteClick(Sender: TObject);
begin
if list.Selected <> nil then
begin

if MessageDlg('Are you sure you want to Delete the selected message(s)?',
    mtConfirmation, [mbYes, mbNo], 0,) = mrYes then

POP1.Delete(list.Selected.Index + 1);
pop1.Disconnect;
list.Refresh;
list.Selected.ImageIndex:=2;
end
  else showmessage(' No messages selected for removal');
end;

Thanks