Interestingly, a recall when there's really an issue ("Dear boss: You're an idiot and everyone knows it. Drop dead!") will never work. But a fake recall, one that prompts people to not only read your message but study it for whatever salacious bit of dirt you're now trying to hide, will work. So if you want people to really focus on your E-mail, a little recall never hurt.
Despite the efforts of helpdesks everywhere, the belief persists among retail users that E-mails sent externally can be recalled. Even though they can't be recalled, people still try. But we're now seeing folk using the misunderstood recall E-mail function to do the opposite—to get people to pay attention to their E-mails. The tactic should be applauded for its diabolical, Machiavellian nature. A message is sent, and then—about a minute later—recalled. Nothing in the world is more irresistible than an E-mail that is supposed to be deleted unopened.