RGP stands for Redemption Grace Period. The Redemption Grace Period is a thirty (30) day period that begins after a registrar requests that the registry delete a domain name. The Internet Corporation for Assigned Names and Numbers (ICANN) has required that registries implement this facility to allow the original registrants (domain name holders) to redeem a deleted name.
The reason for the introduction of the RGP process is to provide additional time to catch erroneous deletions before the name is made available for re-registration.
When a name enters RGP, it is removed from the zone file (if it was originally in the zone file). As a result, any Internet services served by the domain name will be disabled (e.g. e-mail or a Web site). The registrant must act IMMEDIATELY if he or she wants to keep the name.