JBMail   
http://www.pc-tools.net

JBMail is a compact and portable secure e-mail client that supports SSL/TLS encrypted POP3 and SMTP. The software has been designed for simplicity, security and on-line mailbox access meaning that mail is manipulated remotely and NOT stored locally. Delete spam or large attachments without having to first download them! This portable software does not require installation, registry keys or even temporary files. JBMail can be run from a CD or floppy disk, yet it has all the essential mail client features including attachment support, advanced junk filtering, address books, and defenses against destructive attachments. It is naturally immune to HTML and scripting attacks. With its secure design, small size, and SSL support this client is ideal for the road warrior or security-conscious remote mail user.

CliMail   
http://software.blizzard-media.com

CliMail is a set of command line utilities designed to send and receive email. CliSendmail sends email to recipients via the SMTP and SMTPS protocols. CliGetmail receives mail from either POP3, POP3S, IMAP or IMAPS mailboxes. CliMail works best in a scripting environment and has the following features. CliSendmail - send email from the command line, specify CC recipients, specify BCC recipients, send attachments, set delivery notification email address, send email through a firewall (set firewall host, user name, password and type), send HTML formatted messages, set importance level, add your own RFC 822 compliant headers, send mail through servers that require a login, send mail through servers that require CRAM-MD5 authentication mechanism, specify alternate port for an SMTP server, set the priority of an email message, set the reply to address, set the email address to send the read receipt to, send email through SMTPS servers. CliGetmail - check email from the command line, check email through a firewall (set firewall host, user name, password and type), check both POP3 and IMAP accounts, send plain text message, reply to a message, list all messages in a specified mailbox, display messages, delete a message, specify alternate mail server port, check email on POP3S or IMAPS servers.

Crypto Anywhere   
http://www.bytefusion.com

Crypto Anywhere is secure email on the move ! Crypto Anywhere is small enough to fit on a single floppy or USB key chain drive and so easy to use your grandma will be using it. Don't have a computer yourself but want to protect your web based e-mail at your local internet cafe ? Crypto Anywhere is for you ! If you suspect your employer is reading your private email, put an end to that. If you run Crypto Anywhere from a floppy disk or USB drive, you can encrypt your email without even installing software on your workstation. With Crypto Anywhere you can send and receive secure mail to and from anyone with an email account - the recipients do not have to be "crypto savvy" or even have Crypto Anywhere themselves. Crypto Anywhere implements trusted, industry standard, strong encryption algorithms based on RSA public key encryption, the Twofish block cipher and the ISAAC random number generator. Crypto Anywhere e-mail is compatible with SecExMail client based and SecExMail Gate server based encryption.

Crypto Anywhere - OpenPGP Edition   
http://www.bytefusion.com

Secure Email .Standalone or integrated with Outlook Express. Can decrypt and encrypt messages to friends using PGP, OpenPGP, SecExMail and many more. Crypto Anywhere allows you to make a travel floppy which can be used in internet cafe's or at work. You don't even need to install the software - just run it from the floppy disk or USB thumb drive. Encrypted messages can be sent to friends who don't even have Crypto Anywhere. Registered users can use Crypto Anywhere for commercial purposes. Crypto Anywhere implements trusted, industry standard, strong encryption algorithms based on RSA public key encryption, the Twofish block cipher, ISAAC random number generator and OpenPGP.

SecExMail Gate   
http://www.bytefusion.com

SecExMail Gate is an email proxy server which encrypts and decrypts messages on your corporate network in real-time. This proxy server integrates with your existing corporate infrastructure and operates in conjunction with your SMTP/POP3 mail server. SecExMail Gate implements open standard encryption algorithms to create a seamless security framework to protect the privacy of your corporate email on the public internet. No additional software on the e-mail workstations on your network is required.