I have only used the free version but can tell you that I love it. I opted to buy acajoom pro based on the price and the feature set and am very happy with it. Now with that said the top version of Acymailing does offer more features for more money but I did not need the full feature list. For example, the top version come with auto responder and bounce handling, I did not need the bounce at this time but did need the auto responder. In sum both these programs are great because I have used them and am very satisfied with them. I will probably buy the top version of this program for one of my websites.