I had one of those unsolicted scam invoices from the Domain Renewal Group. They send out official looking invoices hoping to trick people to sign up for their "services" at a greatly inflated cost of staying with your existing registrar. Buried in the test they'll say "this is not a bill" but that is just their lipservice to previous legal smacks on the wrist.
One common feature of this con trick is that in the UK they use the post mail box shop located at 56 Gloucester Road. DRG make out they have an office located there by including Suite 526 in the address. The owners of the mail box shop at 56 Gloucester road should hang their heads in shame at their continued support of the Domain Renewal Group scamsters.
What is more annoying is the Royal Mail appear to officially support the actions of DRG by providing bulk mail rates under licence HQ9321