Loads of e-mail marketing horror stories from Jared Blank in a ClickZ article called “E-Mail May Cost More Than You Think”:

“E-mail messages are inexpensive and easy to create, factors that have led many marketers to use them carelessly. Just as many of us send e-mail to friends with little thought as to how it will be received, marketers frequently send e-mail without considering the message’s branding implications. How else can you explain the errors I’ve noted above?”