rocknbil - 8:00 pm on Mar 12, 2010 (gmt 0)

maybe implementing a "verify email address" link similar to how forums work

I say, no, don't do it, this is going to create barriers for your users. It would be on the same level as requiring registration to order the item.

And hey, what if your verification email goes into their spam box and they never see it? <poof> they're outta there.

Unfortunately I don't have other helpful advice, my clients rarely get fraud orders, just the odd few requesting shipment to Nigeria. :-) But I'm wondering about this . . .

I receive a declined credit card response, and then try to contact them with obviously no response.

I've read this four times and it sounds like, to me, the order is being placed and you're manually trying to run the card after the fact. (?) If you're integrated with a credit card processor, you'd never know or hear about the decline unless you have an email trigger for it, in which case . . . there's no reason to fret over it, if it's declined, they're already in trouble.