In past I have had a serious bout with a few male members... who had also resorted to hack my personal email domain and send silly messages on my behalf..........which I caught through YAHOO people...but remained quiet.....
Good thing you caught the perps. If something like this ever happens with your PM facility on GS please let the administration know, the technical features allow to track not only where the post came from but what computer was used. This way people can not muck about etc with other's ids etc if you know what I mean. Those sort of logs always come in handy in such situations.