It has been two and a half years since Research in Motion (RIM) began licensing its BlackBerry software to handset makers like Nokia. The company’s decision – which we describe in this month’s “Briefcase” section (see “The Willing Partner”) – has paid off handsomely for the company, whose stock price has risen more than 800 percent in that time. While our story credits RIM’s success to its smart approach to licensing, there is another reason the company is doing so well: the business world has fundamentally changed the way it thinks about e-mail. This may not be all to the good.

When it first entered the workplace, e-mail was thought to be an “asynchronous” mode of communication. That, in fact, was part of what made it so appealing: unlike the telephone (or the person dropping by your office), an e-mail could be safely ignored until you wanted to reply to it. But before long, workers were expected to monitor incoming e-mail, much of which was time sensitive. The arrival of the BlackBerry amplified e-mail’s urgency: suddenly, it wasn’t just something you paid attention to in the office. E-mail was hitting you at home, in your car – everywhere, in fact.

Is this bad? In April, Hewlett-Packard reported results of research it commissioned on the effect of e-mail, instant messaging, and the telephone. Glenn Wilson, a psychologist at the University of London, conducted tests involving 80 British workers and claims that technological distractions make workers temporarily dumber by 10 IQ points – that is, more than two times dumber than if they were smoking marijuana.

HP’s press release was quickly picked up by major newspapers; it was fun to report that e-mail was making us stupider than pot. But pot isn’t the most obvious drug analogy for wireless e-mail. BlackBerry’s fondest fans have given their device a nickname: they call it “CrackBerry.” Yes, wireless e-mail is often extremely helpful – and many who have it couldn’t do without the technology. But its sheer pushiness should give us pause. Companies that dole out wireless e-mail devices should set clear expectations about how these gadgets can be best used to improve efficiency – without inducing stupidity.