1. See autogenerated mp3 spam results which can be easily filtered out using the Junk filter & generally only takes 2-3 additions before the filter recognises it as junk.

2. Keep in mind almost all windows systems are set up by default do hide the extension of the file. So you may find a particular file has an exe at the end without knowing. Such as "All my L*ve".mp3.exe but all you see is the " " .mp3!!!