[UPDATED 7/2/12: Please note, the 20,000 bonus mile offer has expired. I’m leaving this post as is for the sake of archiving the offer.]

A reader recently emailed me wanting to get into the mileage-earning credit card game, but was declined by the big three – American Express, Chase and Citi – for having less than ideal credit. Let’s face it, not everyone is equipped with a credit score to really take advantage of the big sign up bonuses the major players offer.

The Miles by Discover Card, though, is an option for people with imperfect credit who want to begin earning miles to redeem for free travel. And it does come with a 20,000 mile bonus when you meet a minimum spend threshold. Now before I go on, I should say that I don’t think anyone should sign up for a card requiring a minimum spend if they’re not in a financial position to do so. That may be common sense, but I’m just sayin’.

Here are the details for the Miles by Discover Card offering up to 20,000 bonus miles:

• Earn 10,000 bonus miles when you spend $2,000 on the card within the first 6 months. Earn an additional 10,000 bonus miles if you spend another $2,000 on the card in that same first 6 months (for a total of $4,000 and 20,000 bonus miles).
• Earn 1 mile for every $1 spend on the card.
• No restrictions on travel – fly any airline, book any hotel or car, with no blackout dates.
• No cap to the miles you can earn.
• Travel benefits include secondary collision damage insurance when you rent a car with the card.
• No annual fee, no rewards redemption fee and no additional card fee.
• 0% intro APR on balance transfers for 12 months.
• Regular APR between 10.99% – 20.99%, depending on your creditworthiness.

So how does the program work, exactly? Basically, 10,000 miles equals a $100 travel credit that can be redeemed after booking any airline, cruise, vacation package, hotel or car rental. You pay for the travel purchase on your Miles Card, then within 90 days of the transaction posting, redeem the credits in your account to cover the cost. So while you initially charge the purchase to your card, you can then defray or zero-out the total cost with your miles. You must redeem your miles in 10,000-mile/$100 increments.

Where do you book your travel? You can book with any airline, travel agent or online travel agency like Expedia, Priceline or Orbitz.

This card does not offer the flexibility to transfer miles into your frequent flyer accounts like the Chase Sapphire Preferred or Chase Ink Bold, but that’s sort of the point of the card. It let’s you fly any airline and redeem the credits directly within your account.

Again, it doesn’t compare to the big three card issuers’ bonuses out there, but it can be a good start for those who want to start earning free travel by using a credit card.

I do receive a referral credit for anyone who applies for the card through the links in this post. I remain grateful for those who do.