I received a private note. I responded to the private note. There was no indication that the response was actually sent. There was no sent mail, nor was there any notice that "you're mail has been sent". It simply took me to the new mail page. I resorted to creating a new note rather than "replying", and then received indication that the note was sent. I have no idea whether the initial "reply" mail actually got sent.
I think this is a problem that should be looked at.