I've noticed there are a couple of ISPs that automatically click links in email messages (I'm assuming to check them for spam or malware). Unfortunately, these clicks are showing up in my click report and skewing the numbers. The most notable offender is @rediffmail.com -- it appears to follow the first link in the text-only version of the message.
Any way we can get Campaign Monitor to just filter these out of the link reports? I haven't checked, but I assume they use a distinctive user agent. Let me know if I can help provide any examples or additional data.
It appears that Campaign Monitor is registering HEAD requests as a click. I think this is probably not a good idea.