You think that the email spam industry collectively employs more than 500,000 full-time voting adults, rather than a relative handful of humans and tons of bots? It's fine if you do, my hunch is just different.
LOADS of what people classify as "spam" is simply stuff they signed up for and forgot about. Just last night a client had someone write in saying "I'm not getting your emails!". After some back and forth they had - 2 days prior - marked it as "spam" because they didn't recognize the name of the list, and so weren't getting any more mails (or, they were getting junked).
You may be able to make an internal distinction between "the spam industry" and "email" but many people can't or don't. Or perhaps more to the point, many people classify spam as "anything I don't like or didn't ask for" (even if, by dint of entering in to a transaction, they do in fact grant permission to get necessary emails now and then).
