MailStore - MailStore Home - A 100% free single-private-user desktop solution
OpenPGP Keyserver - Pool of places to publish and search OpenPGP public keys.
MailSteward - MailSteward : The Ultimate E-mail Manager for Mac OS X
SKS OpenPGP Key server - The place to publish and search OpenPGP public keys.
Mail Backup X - Your one stop mail backup and archiving tool for Mac.
MIT PGP Public Key Server - The place to publish and search OpenPGP public keys.