Registrar Data Escrow (RDE) is an ICANN mandated process that registrars must follow to store a copy of the customer’s whois information with a third party. Smaller registrars will deposit the information weekly (larger registrars in higher frequencies) on the server of the RDE provider in an encrypted format. Should your registrar go out of business, this would be the information passed on to the new registrar who takes over the domains and your clients. Going forward, registrars offering whois privacy services will be obliged to deposit the underlying whois information (without privacy) with the escrow provider.
ICANN had initially selected Iron Mountain as a Registrar Data Escrow provider. As of March 2018, DENIC e.G. also offers Registrar Data Escrow services through DENIC Services GmbH & Co. KG, a sister company of the German registry. If the registrar uses Iron Mountain or DENIC, there are no additional charges to be paid as ICANN is paying for their fees. Some registrar system providers might, however, charge fees to enable the deposit service on their end. Registrars are also able to choose from other approved providers but will have to pay those directly.