You may be able to set up filters to automatically trash everything sent to incorrect addresses. It might be fairly annoying, but it should certainly be possibl

You may be able to set up filters to automatically trash everything sent to incorrect addresses. It might be fairly annoying, but it should certainly be possible. Just set a filter for firstlast@gmail.com to send them to spam. Also, software such as mailwatcher allows you to bounce emails after they've been received by the server if you think it necessary.