kuvert automatically signs and/or encrypts outgoing mail using the PGP/MIME standard (rfc3156), 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.
&rw (yeah, Robert Waldner, that's right) says:
kuvert is the perfect tool for us lazy paranoids out there. 'nuff said.
I seriously doubt there are that many paranoid people out there. But plenty of lazy people (don't forget to vote, Americans).
More information on this package can be found on whatiskuvert and the Debian web site.
(If there is a package you would like to see featured here, go to the userinfo page and follow the directions there to submit your entry.)
Now available in RSS and ATOM flavors too.
Update: Fix homepage URL (which isn't really much of a homepage anyway, seriously). sigh