Clients are strongly urged to refrain from using ANY service or paying ANY invoices from Domain Registry of America.
This company sends out advertisements for domain services which are designed to look like invoices. Unless you read every single word of the mailing, you could easily be fooled into paying the fake invoice, which also causes your domain to be transferred to their control. This is all despite a court decision forbidding them from engaging in deceptive practices.
The only way to make them stop once and for all is to starve them. Refuse to take the bait!