WinZip Companion for Outlook   
http://www.winzip.com

WinZip Companion for Outlook makes it easy for users of Microsoft Outlook to zip and encrypt attachments to outgoing email messages. Zipping attachments saves transmission time, conserves space in Outlook mailboxes, and saves disk space for both the sender and recipient of the e-mail message. The Companion can be configured to automatically zip your attachments, ask whether or not you want them zipped, or let you zip and attach files manually with just a few mouse clicks. Toolbar and menu items allow you to control the Companion's functionality on a message-by-message basis. In addition, sensitive attachments can be easily protected with the same built-in advanced AES encryption found in WinZip 9.0. For more information, please visit the WinZip web site at www.winzip.com.

AutoZip for Outlook   
http://www.wiredbox.net

AutoZip is an add-in for Microsoft Outlook 2000/2002 (XP)/2003 which enables you to automatically compress attachments of outgoing message with a single click. If you send e-mail messages with attachments sometimes the recipient is not able to get the message because a message or mailbox size has been ecxeeded because the attachments you sent are too large. Normally you would now compress the attachment manually and create a new message including the compressed attachments. A boring and time consuming job. Let AutoZip for Outlook do this job automatically for you. AutoZip automatically compresses the attachments of your outgoing e-mail messages before they are sent. Just add or drop in the attachments in your message and you are done.

iOpus Secure Email Attachments - Encrypted and Self-extracting   
http://www.iOpus.com

Let's face it, in the real world many people simply aren't willing to buy and install a specific encryption package just to be able to read a couple of files you send them. With iOpus Secure Email Attachments (SEA) they don't have to, because you can send them 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. In just a few moments, you can create an encrypted, compressed (ZIP) attachment with your sensitive documents. Ideal for sending information by email or making secure backups. Thanks to compression, iOpus SEA packages are up to 95 % smaller than the original files, saving time and money for e-mail transmission. The recipient requires no special software, because iOpus SEA packages decode themselves after the password is entered. If desired, your company logo, a custom message, and a link to your home page can be displayed: the perfect combination of branding and security. In addition, your disclaimer may be displayed: your client has to accept it before decrypting the iOpus SEA package.  iOpus SEA uses the Blowfish encryption algorithm with a key length of up to 448 bits. Blowfish encryption is so strong that it has never been cracked yet. In fact, most experts agree that it cannot be cracked with current computer technology and that includes supercomputers! Your time is not worth waiting for your computer to do what you want him to do. iOpus SEA is very fast. Encrypting or decrypting a file hardly takes any longer than copying it. iOpus SEA protects your data not only on its way across the internet, but also on the recipient's PC. Easy to learn - no training required 

absoluteTools-SendMail   
http://www.abspdf.com

absoluteTools-SendMail is a easy to use ActiveX COM Control that enables you to send email from your Windows applications using VB, VC++, Delphi or any other ActiveX COM aware programming environment. Now with a free .NET component version (same license, no additional charge). Send emails to multiple recipients (To, CC, Bcc) either in plain text or HTML, adding any number of attachments and inline images. Automatically embeds images, javascript and css from external local files referenced by the HTML. With the supplied VB, VC++ and .NET sample projects and online help you'll be able to send your first emails in minutes!

MailBee SMTP   
http://www.afterlogic.com

MailBee SMTP is a powerful and easy to use COM object which enables ASP and Windows applications to create, send and queue mail to SMTP servers. Secure authentication, email validation, correct MIME composer, multiple attachments, and much more. Can be used in conjunction with SSL, SMIME, POP3 and IMAP4 components. Royalty-free distribution.