Download goods. How to prevent invalid CC?

[Guest]

I process all my credit card sales off-line. It means The user send all the CC info, I process it then I send the goods.

Now, I'm selling somethings that are download able. How can I prevent bad users to enter a bogus/fake Credit card, just to access the download link, get the file then the credit card returns as a bad?

Something like put that sale on hold until I get the CC approval, then send e-mail to the user with the download link?

 

Thank you for ideas