You can look at arin.net to see who owns the IP address. As far as stopping the emails from your own email - there is not too much you can do. It is very easy to set up a form to create these emails - almost anyone can do it with just a little programming knowledge.

Just make sure your email server is secure so emails are not being sent from your email server

-Corey

Setup an SPF record [webmasterworld.com] for your domain. That qualifies the senders of the mail. You can then filter out mail that doesn't pass the SPF test.