This morning I spent a few minutes going through my Gmail spam folder, looking for legitimate mails that might have been accidentally marked as spam by the Gmail system. It's rare, but it happens.
I found a message from 3GStore.com, a company I purchased an antenna from, once upon a time. I really don't want to receive emails from them. I'm not likely to be a repeat customer, and I'm eager to get "edge case spam" - things that might be considered spam or not, maybe from companies that I signed up for, out of my mail stream, so that I can trust my spam folder to contain "true" spam, because I'm a bit of a data geek and want to be able to write a script that parses that information and logs it.