We recently implemented Biscom Delivery Server for a professional services firm.
This software allows a business to host their own secure email and file delivery system. A button is added to Microsoft Outlook allowing one-click security to encrypt and protect sensitive information from traveling openly over the Internet, as email does. Large files can now be sent to/received from customers securely, while reducing the problem of large attachments clogging the email system.
More information on this software is found here: http://www.biscomdeliveryserver.com/