I have just been (nearly) bitten by a few Registration Services Scams.
Here is how it works:
After a patent has been received in a patent office, the address of the inventors are published and become public knowledge. There are some (Do Evil) companies that scan these addresses and send very official requests for fee’s for supposed services like “Registration Service Fees”.
These letters and envelopes seem so original that I was about to fall for the scam and pay the fee. The only signs of a scam was the payment method which is different than the normal methods used to pay for Patents.
In the end I called my patent lawyer and asked her what the letter was about. She confirmed that it is a scam.