We've been using clearalist for about 5 years now to verify our contacts before we send them mailings or newsletters since they do an excellent job of keeping my lists clean! They have helped us improve deliverability by leaps and bounds (we used MailChimp previously). Their customer support is top notch as well - responsive at all times during business hours in most cases which makes things easy when something does go wrong with their system. I can't think of anything that would make me dislike this product other than perhaps if there were more features available but those are minor issues compared to how much value these guys provide. Verified mailing addresses so we don't get bounced back due lack of interest/spam filters etc.. Also helps keep up delivery rates because people know what's coming next time around vs sending out multiple messages hoping one might stick :) Great tool overall!! Highly recommend. A must use especially considering how cheap pricing is compared to competitors such as Constant Contact who.