Nice infographic on the Marketo blog regarding the evolution of spam, along with a list of 5 rules for not being a spammer. Take a look.

But remember rule #6 which is not on their list:

"Do not send unsolicited commercial email to someone who has not previously given you permission to do so."

If every day you get 1000 unsolicited emails, one each from 1000 different companies, all of whom follow rules 1-5 of "How to not look like a spammer" would you say you had a spam problem or not? How long would it take you to opt out of 1000 emails/day?