Symantec Desktop Email Encryption!

Gpg4win is an installer package for Windows (2000/XP/2003/Vista) with computer programs and handbooks for email and file encryption. Both relevant cryptography standards are supported, OpenPGP and S/MIME. Gpg4win and the software included with Gpg4win are Free Software (among other things free of charge for all commercial and non-commercial purposes).

GPGTools is an open source initiative to bring OpenPGP to Apple OS X in the form of an easy installer package. This allows you to sign, verify, encrypt, and decrypt files and e-mails. Read the introduction to get a detailed idea of how PGP works.

GPGshell is a Windows GUI for the GNU Privacy Guard - an open source software suite for public-key cryptography compatible with PGP. It provides a simple-ish interface to manage the encryption keys, encrypt and sign files, check the signatures and the like. It is freeware (though, unlike GPG, not free software) and with little effort can be made portable.

The perfect solution for regulated industries use of email to communicate protected health information (PHI); Paubox email solution is HIPAA compliant and will sign Business Associate Agreements. Great for small to medium sized practices required PHI compliance, but don't have the resources for an expensive IT management and confusing enterprise solution.

p=p is a cyber security solution which protects the confidentiality and reliability of communications for citizens, for public offices and for enterprises.

Switch Secure Email enables users to send and receive sensitive data securely, including emails and file attachments. Free desktop apps enable users to send secure emails directly from Microsoft Outlook, while Switch Web Access means users can send and receive secure emails without downloading any software. Sending encrypted large files using Switch also overcomes the usual attachment file size limitations found in most email clients.

PGPigeon is a simple but powerful OpenPGP-compatible message encryption webapp based on the openpgp.js library.