There is considerable gratification that comes from forever being needed, wanted -- popular, even. "It's sort of the way you used to feel about mail arriving from the postman," explains Sarah Crichton, the publisher of Little, Brown. "Possibly, just possibly, there would be something wonderful in one of those envelopes that would delight you, make your heart race a little faster. The difference with e-mail is that it keeps arriving all day long."

All this compulsive checking and replying necessarily carves up days into smaller and smaller bits. What gets sacrificed is the depth and richness that grows out of sustained, absorbed attention to a single task. Instead, multitasking -- the capacity to do more than one thing at a time -- has become a desirable skill for overburdened executives. "I can do my e-mail while I'm talking on the phone," says Lauren Zalaznick, head of original programming for VH1. "I know it's rude, but I can also take a meeting and do e-mail at the same time. Basically, e-mail goes with almost everything."

Zalaznick is sitting across the desk from me as we talk. She never strikes me as harried, but there are several odd moments when I sense that she isn't completely there. Only later does she acknowledge that during our time together, she received fourteen e-mails and managed to quietly respond to most of them, tapping away at a silent keyboard hidden below desk height. As far as she's concerned, there's no choice. If Zalaznick doesn't multitask, there's no way to get all of her work done -- much less leave the office in time to hang out with her two young children and put them to bed.

"There's no question that e-mail increases efficiency," explains Esther Dyson, who heads the high-tech consulting company EDventure Holdings. "The problem is that it increases the efficiency of the next guy, too, so no one really feels more efficient."

The next time I experience what I have come to call The Pause is during a telephone conversation with Sarah Crichton. This time, I can't resist a small dig. "You don't happen to be answering your e-mail, do you?" I ask.

"How did you know?" Crichton replies, slightly abashed. Then she makes a confession: "During meetings in my office, when I have to dig in deep and really think about something that makes me antsy, I'll often swivel in my chair and start answering e-mails. I don't even notice I'm doing it, but the people I work with have learned to call me on it."

Andrew Heyward, the president of CBS News, has recognized another way that e-mail costs him. "It's a refuge when you don't want to grapple with something else, but it also works the other way," he says. "Whenever I have a free moment now, I turn to e-mail. It's probably taken away the last few minutes in my life that were available for pure reflection."

For many, leaving the office scarcely means logging off. "The umbilical cord is longer than it's ever been," explains ABC's Iger. On the weekends, like many of his fellow executives, he still manages to check his e-mail at least three times a day -- and does so just as frequently when he's in Tokyo or Shanghai on business. America Online recently commissioned a study of Internet use and found that 47 percent of users now take their laptops on vacation, and 26 percent check their e-mail. "I've played the game of not taking my laptop on vacation," explains Barry Schuler, president of AOL Interactive Services. "What happens is that you sit there on the beach, gazing out into the ocean, but you can't relax because you're thinking about how many e-mails are accumulating in your in-box. I finally decided that I'm willing to take a couple of hours each day on vacation discreetly off in a corner doing my e-mail. It's worth feeling like a jerk in order to know that I'm on top of everything and I'm not going to return to 1,000 unanswered e-mails."