Does it seem as if every time you open your mailbox, someone is trying to sell you plastic money?

American Express. Discover. Visa and MasterCard. From banks all over the country. Credit cards linked with special-interest organizations like the Sierra Club, your college, a public television station.

They offer you $2,000, $5,000, $10,000 worth of credit. Sometimes the credit line is preapproved, yours for the signing, no questions asked.

Lenders find you by buying lists of customers who appear to meet their credit criteria. Often, they buy from credit bureaus. They may ask for names of customers who already own credit cards and are making the minimum payments on time.

"There's not that much concern about the number of credit cards you already have, and I think this a very serious flaw in the system," says Ken McEldowney, president of the board of directors at the Consumer Federation of America.

Solicitations may go to families who are already carrying too much debt. If they realize that they're in trouble, they will throw the application away. But some are true spendaholics who cannot resist another $2,000 worth of credit. That preapproved loan may be the one thing that brings down their whole house of cards.

To banks, a certain percentage of defaults are an expected cost of doing business. They charge a high enough interest rate to cover that loss. But offering credit to uncontrolled spenders is like providing crack to drug addicts.

"I got a $10,000 credit card in the mail and thought, 'That banks knows something I don't know,'" says California housewife Betsey Lenahan, who once attempted suicide in her despair over debt.

"I knew that I couldn't afford more credit," she said. "But I figured that if the bank thought I could, it would be all right." Lenahan ran up $11,000 on six credit cards before getting help from an antidebt-support group.

Terry Dempsey, also of California, charged $40,000 to his credit cards when he was earning only $32,000 a year. He borrowed from one card to make minimum payments on another. In one year, he paid $26,000 in interest.

In theory, neither Lenahan nor Dempsey should have been able to get so many cards. A prudent lender screens every applicant individually. You should be turned down if you have so many cards that your availble credit line is more than your income can support. It doesn't matter that you are not now using all that credit. The point is that you could in the future, and it might get you into trouble.

"There's a big difference between 'preauthorized' and 'prescreened' credit" in mail-order offers, said William Dobbins, a vice president of Chase Manhattan Bank.

With the latter, you are screened as a likely candidate for a new card but still have to pass an individual credit check. If you fail, you'll be turned down. "Looking at people who are using a lot of cards, we ask whether it's reasonable for them to have that much credit," Dobbins said.

It's only the "preauthorized' credit offers that give spendaholics more rope with which to hang themselves.

"Sometimes the mailing lists used by banks aren't sufficiently purged {to remove those with too many cards}," said Craig Ulrich, general counsel for the Consumer Bankers Association.

In fact, getting more and more cards might catapult you onto a prime mailing list.

"A lender might say, 'Citibank gave this person $5,000, Chase gave him $5,000, so let's give him $10,000,'" Ulrich said.

"My credit is squeaky clean," Dempsey said. "I was paying with cash raised from other credit cards, but I always paid the minimum. Creditors love me. They want me back."

They won't get Dempsey and Lenahan back. They've learned the hard way to throw out mail-order credit offers.