Are you a collector of American miles? Do you shop online? If you answered “yes” to both questions, this promotion is for you.

Through June 30, AAdvantage members can earn bonus miles when making purchases through the AAdvantage eShopping portal. How many miles? The offer is being promoted as a Mystery Bonus Event, which means you’ll have to log in with your AAdvantage credentials to find out.

My Mystery Bonus was 2,000 bonus miles after spending at least $500. So, an extra four miles-per-dollar, over and above whatever payout is on offer from participating merchants.

Your mileage may vary.

Deal or No Deal

Any bonus is better than no bonus at all. This one isn’t bad, although the $500 spend requirement will make it a stretch for many consumers.

More generally, if you’re not earning miles by shopping at the airlines’ mileage malls, you should be. There’s no reason not to; the prices are the same. And by making your purchases through the airline’s portal, you’ll be earning miles — typically between one and 10 miles per $1 spent — that you don’t get when dealing direct through the merchant.

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Making a good deal even better are the periodic bonus promotions, like this one, that amp up the mileage-earning. Such offers generally proliferate around Christmas and other heavy buying periods, although recently the airlines have used back-to-school shopping and other recurring events as the hook to hang their promotions on.

So, if you’re going to be shopping online anyway, it always makes sense to do so through an airline’s mileage portal, to earn miles for the purchases. And when there are extra bonuses in place, it makes even more sense.

As always, when shopping via an airline’s mileage mall, you must first stop at the mall’s landing page to log in with your loyalty-program credentials. Thereafter, purchases at any of the mall’s hundreds of participating merchants can be tracked and credited to your account.

After 20 years working in the travel industry, and almost that long writing about it, Tim Winship knows a thing or two about travel. Follow him on Twitter @twinship.

This article first appeared on SmarterTravel.com, where Tim is Editor-at-Large.