(FORTUNE Magazine) – TUPPERWARE PARTIES in the boardroom? Ding-dong, Avon calling, during coffee breaks? Dunhill tailors measuring deskbound executives? The workplace hasn't exactly turned into a shopping mall, but fewer employees are rushing to Woolworth's at lunch hour. Says Neil H. Offen, president of the Direct Selling Association: ''Companies are selling where customers want them -- on the job.'' Americans are working longer hours than they used to, earning more money and leaving less free time in which to spend it. That is a marketing opportunity with appeal for an increasing number of companies. In the vanguard are enterprises with long experience in direct selling: The Tupperwares and Mary Kays of the world are following their customers, and that means invading offices, since more than 50% of U.S. women work. The trend poses a new management problem for employers. Should they forbid employees to buy and sell personal products on company time? Tolerate it? Encourage it? Those who haven't decided will likely have to soon. Avon, which once sold products only door-to-door, picks up 25% of sales from buyers at businesses. Pamela Cook, a leading Avon saleswoman who peddles most of her beauty wares at West Virginia companies, says, ''All these supermoms with ten- hour-a-day jobs tell me I'm their ray of sunshine.'' Direct-selling companies need something to brighten their future. Their U.S. sales had been flat from 1980 to 1986 and last year rose only about 3%, to $8.62 billion. By marketing in the workplace, companies gain access not only to consumers but also to potential salespeople. Many of the 4.5 million direct sales representatives in the U.S. are women who hold other jobs. Their prospective customers sit at the desks around them. Salespeople who don't hold other jobs get into offices through acquaintances or by walking up to the receptionist and asking to come in. Avon, America's largest direct seller, has begun training its 400,000 salespeople to operate in the workplace. ''Our reps are the smartest people in the world,'' says Phyllis B. Davis, head of U.S. sales and distribution in Avon's beauty division. ''They've already been selling outside the home, but we are finally acknowledging this strategy with advice and support.'' Some Avon tips: Sell only during coffee and lunch breaks. Be a walking Avon advertisement (wear Avon perfume and lipstick). If you hold another job, give your boss a small Avon present, such as makeup or bubble bath. All this helped the U.S. beauty division post record third-quarter sales. Even products with no role in the office can be sold there. Tupperware, the plastic-kitchenware king that invented suburban Tupperware parties as a distribution channel, is pushing a new form of office sociability called rush- hour parties. These occur near the end of the workday and are set up by Tupperware's 85,000 reps. Says K. Douglas Martin, president of Tupperware North America: ''We used to say you can't buy Tupperware unless you come to a home party. Now we come to you.'' About 20% of Tupperware's estimated $320 million in U.S. sales last year were outside the home, and often they were the easiest sales to make. ''I don't have to give a big spiel,'' says Chicago's Denise Kaluzna, one of Tupperware's leading saleswomen. ''Working people want to buy quickly.'' Kaluzna claims she can sell up to $2,500 of Tupperware in a two-hour office party, vs. $400 of plastic at a home bash. Mary Kay Cosmetics is giving a face lift instead of a party. Products that account for 85% of sales have been revamped with new packaging and more fashionable colors, primarily to increase appeal to working women. Says Margaret Leonard, who sells in Manhattan business firms: ''Working women buy more in the office because they are not looking at the wallpaper that needs replacing. They feel richer away from home.'' Many companies insist that employees conduct outside activities, especially freelance selling efforts, strictly on their own time. BankAmerica and American Airlines forbid any soliciting on the job. AT&T and others take a more benign approach as long as employees don't lose too much time from their jobs. Says Burke Stinson, a spokesman for AT&T: ''We don't crack down as long as the employee doesn't set up shop on a regular basis. We don't want telephone operators trying to sell lipstick when they are looking for a phone number.'' Some bosses applaud the trend because it keeps more employees on the premises during lunch and presumably shortens their lunch breaks. ''Office ! shopping is a time-efficient way to keep employees happy,'' says Stephen Heymann of the New England Consulting Group. Other managers figure that if employees are earning a second income, they'll be less likely to demand higher pay. AVON AND TUPPERWARE, realizing they could be thrown out of a lucrative market, urge salespeople to keep office hawking low-key. Gaylin Olson, sales chief for Tupperware U.S., advises, ''Don't load yourself down with so many products that you look like a bag lady.'' Amway, the multiproduct company that sells through independent representatives, is an aggressive marketer. But it does not want to test corporate permissiveness. Says William Nicholson, chief operating officer: ''We de-emphasize this selling because eventually it will cause a backlash. It is irritating to pay an employee when he uses your time to work for someone else.'' Alfred Dunhill of London doesn't worry about the boss objecting: Its clients are primarily bosses. Since September Dunhill has been sending tailors with hundreds of fabric swatches to executives on the job. They can set up appointments by phone in major U.S. cities. ''Our customers often don't have time to shop,'' says sales manager John Fairley, who recently measured a busy CEO while he conducted business on the telephone. Typically the Dunhill tailor returns for two fittings. Average sale: $4,000. Top-of-the-line Dunhill suits sell for about $3,000. ''I used to think their suits were too extravagant,'' says Barry Goodman, head of trading for Millburn, a New York investment company. ''But I make money by not wasting time in stores.'' Such services will probably proliferate, says Robert Beauchamp, fashion director of Esquire magazine. He adds, ''Soon it will be a normal business question to ask, 'What tailor comes to your office?' '' Clothiers and makeup artists are not the only office interlopers. Also setting up office dates with harried workers are behavior modification experts, who generally help clients lose weight or stop smoking, and exercise instructors. More marketers will surely follow. As long as Americans continue making their work lives more hectic, office selling looks like a winning proposition for all involved.