how to manually do fraud detection?

[neorder]

if we only use paysystem and paypal.

i saw many are says that they check orders manually, but how they do that? just by a few email?

[Zoomer]

Call up your customers. :)

[AddValue]

It is not quite possible checking on manually. Unless like what zoomer claimed, ring them up.

Even paysystem does encounter fraud CC.

For PAYPAL, it is relatively safe as you need verification. If that party is not a the card holder, there is no way they could process with any payment.

Regards
Doug