The most useful feature for me was being able track my contacts that are not responding or clicking through emails I send out from our website (which we use as part of their signup process). It also made it easy when sending surveys about customer service experiences! Nothing really - just be patient because sometimes you have little control over how long your info stays private until someone decides they want access after all!! You can't delete information if no one has requested yet but once people do request then its gone unless there's another way around this?