Encrypted data could theoretically be recovered, but unless your users are in trouble with the NSA, it's probably not going to happen before we colonize Mars. If you choose to deploy secure messaging, protecting users from themselves should be your first priority. Unlike X.509, PGP's public key certificates can specify more than one public encryption key. Using PGP's admin tool, the administrator can mandate that every user's certificate contain a corporate recovery key in addition to the public key. However, this places a significant amount of trust in the client to honor the ADK policy.
Clients can enforce the addition of a decryption key for all outgoing messages.
Luckily, adding decryption keys is a simple process that doesn't require the entire message to be encrypted multiple times. Inserting an additional decryption key into all encrypted messages lets companies archive all electronic correspondence while still encrypting all incoming and outgoing messages. This is especially useful to companies like financial institutions that are legally required to archive all their correspondence. This conveniently avoids the problem of keeping a ll users' private keys in escrow. A user's private key not only lets him or her decrypt messages encoded in his or her public key, it also creates digital signatures for verifying the user's identity and the authenticity of the message.