The best thing about carrier zone is its easy to use interface, it has an excellent support team who are always willing/happy help you with any problems or queries that come your way. they have amazing features like spam scorecard which helps me identify my low scoring emails along with their helpful suggestions for improvement of same so I can continue improving them till date! i would rate this tool 3 out 5 stars only because there's still room in improvising other functionalities such as mobile application etc but overall not much negative points here at all! keep up good work guys!! we were able track our sending rates from different countries including India & US through real time data graphs provided by carriersizetool itself.