I am working on a little script that reports links to me and them mail me the results. Now obviously, I don't want flooded with emails. So I created a table in my database and when the link is reported 5 times as inappropriate, I will be emailed.

So when 5 users click on the "report" button, I get emailed with the details on the inappropriate link.

I want to make this a little more secure. What if one user clicks on the link 5 times? This would be inaccurate data. Therefore, how can I make sure that each report submission is from a unique IP address.