Send secure email via SMTP with 256-Bit AES encryption and encrypted attachments - Freeware. This one caught my eye "because you can send self-decrypting archives that "unpack" themselves. The recipient just double clicks on the file and enters the password at the prompt displayed. The original files are then decrypted, extracted and written to your disk automatically." - no need for the recipient to install any software. - 560KB

Alan