I"m behind a proxy at work, because that's the only way the large corporation I work for allows me to access the web. Security concerns on their part are one reason, plus my IP address is 192.x.x.x or whatever, inside the company, and you can't browse the internet that way, it has to be translated to another address.

I'm also behind a proxy at home, because most ISPs in Australia do it that way to save money, simply to cache the commonly-requested pages and so on.

If you refuse to sell me stuff just because I'm behind a proxy, you've lost me as a customer. If you choose that route, and I strongly suggest you don't, then I hope to god you're going to tell me so, and not leave me hitting SUBMIT buttons and getting "there seems to be a problem, try again" errors.

I think this question is a case of jumping the gun. Your problem is you're getting fraudulent and/or suspicious orders. You've already jumped to a solution and you're asking for help with that solution.

I humbly suggest that you go back a step. Problem: dodgy orders. Describe the symptoms. Then ask, what are the solutions?
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“Every bit of code is either naturally related to the problem at hand, or else it's an accidental side effect of the fact that you happened to solve the problem using a digital computer.” M-J D