The idea of creating folders in an e-mail reader is not advanced calculus.

FORBES: Serve Your Customer. It Pays Off. Big Time.

Advertisers are willing to shell out big bucks for e-mail newsletters, since reader engagement is much higher compared to the passing attention paid to blogs or Web sites.

FORBES: Internet

Amazon also removed an e-mail address included in a reader's review, which let Web surfers contact the reviewer directly.

FORBES: Magazine Article