Do you keep old e-mail?
mahmud: All the newsletters and business-mailings I subscribed to, but ignored for years, became handy as case studies to see what marketing format works and what doesn't. If you kept getting pricelists from manufacturers/vendors, you easily track the market growth of things and gain valuable insight into the direction of a niche market. This is specially true if and when you pick up AI and data mining as a side hobby and you suddenly figure out ways to infer business insight from large corpora.I say archive them to separate folder and keep them away from your inbox.Sometimes marketers make a mistake and CC thousands of people. Instant targets for your own marketing.