List maintenance is one of the most important subjects in online marketing. Your list is your number one and most basic bottom level output for your promotions. It’s expensive and time consuming to gather, but forms one of the most powerful resources and profit potential you have. For this reason, we need to understand exactly how it works. Throughout my time in online marketing, I’ve tried many different formats. There are clear differences that allow some methods to come out on top, while some fail miserably.