I am able to segment my email list by demographic information that is not easily found elsewhere online! The UI needs some work but this app has been very helpful for me in building lists of contacts who have purchased from or are interested enough about our product/service to provide their contact info as part of an opt-in process rather than simply selling leads. This feature saves time when it comes getting qualified prospects through traditional methods such as cold calling / networking events etc., which can be both expensive & inefficient at times.