SecureZip Standard Edition for Desktop
SecureZIP secures your data using either passwords/passphrases up to 250 characters in length, or ITU-T X.509 digital certificates from Comodo, a certified authority, which are also stored for convenience on in the SecureZIP global directory. SecureZIP also helps you install and use said certificates, which is far more complex than simply providing passwords. However, once you're set with the certificates for everyone involved, you can simply open encrypted email and attachments as you would normal email and attachments--as long as you have a zip reader that understands certificates. At this point, that means PKWare products.
If you want to send a file to someone who doesn't have SecureZIP (which was free as of this writing, but pitched as a limited time offer), you can make the attachment a password protected self-extracting zip. Unfortunately, as an executable file, the attachment might not make it past some firewalls. Alternatively, the recipient can download PKWare's always-free ZIP Reader which also understands the encryption ad security. You have to fill out a form with a valid email address so the company can send you the download link, though, which didn't sit well with some of my testing buddies. It will also complicate your life if you prefer another program such as WinZip or WinRAR for archiving.
But those are minor nitpicks and all told, SecureZIP is a nice solution for securing data, and nearly transparent when you use Outlook and opt for employing digital certificates. It's well worth a look for anyone storing or communicating sensitive data.
Note: This link takes you to the vendor's site, where you can download the latest version of the software. It is currently free for personal use, but it will not be free indefinitely. And business users must pay $40.
--Jon L. Jacobi