From Robert X. Cringely’s “Stream On“:
Mailinator is ad hoc e-mail for those times when just maybe you don’t want to use your regular e-mail address. Say you are snitching on the boss, buying inflatable people, or want 32 different PayPal accounts. Just tell someone—anyone—that your e-mail address is fatman@mailinator.com or skinnykid@mailinator.com, or clueless@mailinator.com or any other address you like at mailinator.com. But this is no dead-end. When people write to you at that address the message will go through. That’s because Mailinator accepts any message going to that domain and automatically assigns an e-mail account to it. But what about passwords? There are none. Anyone can go to Mailinator and check the mail for clueless or any other name. But with so many names and the idea that Mailinator is only for occasional use, who cares?