Thank you so much for the tips guys. We're also experiencing such problem and we were almost scammed once. They were asking the company to give a $20,000 cash advance for the set up fee in their part, or something like that. And they we're asking us to pay through paypal which made us think why go through a third party billing with such an amount. Luckily, our marketing department was able to find out that they were frauds.
And thanks for the link, it's definitely a big help.