When people talk about email marketing, lots of them forget to mention transactional emails. These are the automated emails you get in your inbox after taking a certain action on a website. This could be anything from filling out a form, to purchasing a product, to updating you on the progress of your order. Often, these are plain text emails that marketers set and forget.
Spam is the biggest threat to organic search engines, whose goal is to provide quality search results for keywords or phrases entered by their users. Google's PageRank algorithm update ("BigDaddy") in February 2006—the final stage of Google's major update ("Jagger") that began in mid-summer 2005—specifically targeted spamdexing with great success. This update thus enabled Google to remove a large amount of mostly computer-generated duplicate content from its index.