There are a lot of spam-y ads within the mail UI that are very successful at tricking you into thinking it's an email in your inbox. The natural reaction is to think it's a spam email and attempt to click the check box to delete it, but the checkbox is part of the ad and takes you to the spam website. These potentially nefarious ads have no place on this platform. Please screen your 3rd party ad designs so that they don't include elements that trick people into thinking it's an email in their folder.