If you used a US-issued VISA or MasterCard, or a VISA or MasterCard-branded ATM card, to make purchases or withdraw cash in foreign currency between 1996 and 2006, look for a check like the one below in your mail this week.

Mine was delivered yesterday, so yours might have been delivered a few days ago, or might still be on its way. Check your recent mail. It’s easy to mistake these postcards for junk mail.

These settlement checks being sent to credit, debit, and ATM cardholders are the final act in a legal drama that I first wrote about in 2008.

For years, credit card companies (VISA, MasterCard, and American Express) and card issuers (mainly banks) have been ripping off international travelers by overcharging us for converting transactions from foreign currency to US dollars.

The amounts were small enough that most international travelers — people who travel abroad only occasionally and for short periods — probably wouldn’t notice or care. That’s why the card issuers and transaction processors thought they could get away with gouging each of us a couple of percent.

But for expatriates or frequent or long-term travelers, a couple of extra percent of everything we spend abroad, if we are paying for lodging, food, transportation, etc. with local currency withdrawn from foreign ATM’s, could add up to a non-trivial amount over months or years.

Eventually, people figured out that not only were they being gouged, but they were being illegally gouged, and class-action lawsuits were filed against card companies and banks.

As is usual in class actions, contingency-fee lawyers were appointed by the court to represent “the class” (that’s we travelers) in exchange for a percentage of whatever money they could recover on our behalf. They negotiated a deal in which they would get about $75 million, and the cardholders who had been ripped off would get a total of about $250 million.

There was extensive argument, in which I participated and on which I have reported in a series of prior articles in the Money and Finances section of my blog, as to how that roughly $250 million should be divided up among the claimants.

The lawyers claiming to represent us didn’t really have any reason to care if the settlement was fairly divided, as long as their cut stayed the same size. They hired economists to come up with an algorithm for dividing the money, but they neither had, nor hired or consulted anyone with, any expertise in travel, travel demographics and segmentation, or travelers’ financial habits.

I and others asked the judge hearing the case to withhold approval of the settlement until the algorithm was determined and made available to the affected class, but he refused to do so. Amazingly, the exact algorithm by which the amounts of the checks now being distributed were calculated remains secret!

However, from what was said about the algorithm in filings with the court and at the settlement approval hearing I attended and spoke at in New York in 2009, it became clear that it was grossly unfair, the more so the longer you had lived or traveled abroad. Neither the judge nor class counsel had a clue about expats, long-term travelers, or how we manage our finances and use our ATM cards abroad.

The court approved the settlement anyway. I couldn’t afford to appeal, but some corporate cardholders (raising different issues) did appeal. In time, however, those appeals were all withdrawn or dismissed, and the settlement agreement became final and binding.

Now, following the determination of the still-secret algorithm by some ill-traveled (but well-paid) travel ignoramuses in a smoke-filled back room somewhere, the contractor administering the settlement fund is finally sending checks to everyone who filed a claim. It’s too late to file a claim now, but you might have done so years ago and forgotten about it. (Presumably, the lawyers have also now received their $75 million, and can retire to their private island.)

Everyone who filed a claim and had used their card for a foreign-currency transaction, no matter how small the amount, was promised that they would get at least $25 if the settlement was approved, and more if they had spent more time abroad or could document larger spending.

In the event, so many claims were submitted that there wasn’t enough money in the pool for everyone to get that much. As part of the (secret, remember) algorithm, all payments were reduced by some (also secret) amount. I’d been abroad for about six months during the time covered by the settlement, and received $25.24. Other people got less than $25.

(If you want to help reverse-engineer the final algorithm, post a comment with the claim option you chose — flat amount, days abroad, or a dollar amount of receipts — the number of days or dollars of your claim, and your check amount.)