1. A wrapper that encrypts or signs outgoing mail. kuvert automatically signs and/or encrypts outgoing mail using the PGP/MIME standard (rfc2015), based on the availability of the recipient's key in your keyring. Other than similar wrappers, kuvert does not store the passphrases on disk but keeps them just in memory; if available, kuvert prefers to store the key passphrases with quintuple-agent. kuvert works as a wrapper around your MTA. From Debian 3.0r0 APT