We mask your email links and redirect traffic to them. This is to protect you against spam complaints and to also enable us to track the clicks. The downside is that many tracking counters will not count redirected traffic because they cannot determine the source.
We find that statcounter.com offers a more accurate tracking platform.
If for example you send an ad through us and people clicked to your website and we didn't redirect the click through our servers, then our clients would be able to get the IP addresses (information on people who have clicked) and they would have the means to contact them outside of the campaign (Has to do with the “opt in” process). Of course if they fill out a form you have not gotten them to opt in to you and you can contact them. We are referring to the click throughs that do not fill out a form. Stat Counter is good at capturing redirects at this time.