New (?) malware opens mailto: links

I have started receiving emails from people saying a bunch of “new email” windows popped up with my email address while they weren’t using their computer. It’s the same effect as clicking on a mailto: link in the browser.
My guess is some malware is using their machines to browse my site and click on random links (including ads) – but it’s not smart enough to ignore mailto: links…
Has anyone seen anything like this? Any idea what malware this might be?

what is your site url?

ffog.net

Just talked to a tech support guy who’s helping out a user with this problem. He gave me the user’s IP and I tracked it as coming from clickbaster.net – I’m going to block that site from coming in, hopefully that’ll alleviate the problem.

Sucuri report
http://sitecheck.sucuri.net/results/ffog.net