VPNs provide a means of accessing a corporate network - including a corporate messaging system - securely via the Internet, but without the expense of a dedicated, secure network. A survey we completed in January revealed that, at any given time, a median of 10% of enterprise users access their corporate network using VPNs, demonstrating the importance of VPNs for messaging and other enterprise applications for traveling and telecommuting workers.Although traditional, IPSec-based VPNs are an important element of many organizations' IT infrastructure, they can be difficult and expensive to maintain because they require client-side hardware and software and the resulting support costs. A less expensive alternative is an SSL-based VPN, since this technology permits users to access corporate resources from any modern Web browser without the provision of any client-side software and without the need for dedicated hardware.One provider of SSL VPN technology is Whale Communications, a 4-year-old company in Fort Lee, N.J. Among the company's offerings are Webmail appliances designed for Microsoft Exchange and Lotus Domino that provide access to Outlook Web Access (OWA) and Lotus iNotes, respectively.The advantages these systems provide to an enterprise utilizing VPNs include preventing unknown users from communicating with the Webmail servers, providing secure logoff capabilities that are not inherent in either OWA or Lotus Webmail, preventing anything but application-level information to pass through to the internal network, and preventing unrecognized commands from being transmitted to the messaging servers (which reduces the urgency of patching servers on the internal network).Further, because the appliances do not contain any messaging information or Web pages but instead present themselves to the outside world as the messaging servers themselves, hackers are prevented from interacting with the actual messaging servers, resulting in a very high level of security.Pricing for the Webmail appliances is based on concurrent usage and starts at about $20,000. For enterprises with a significant number of VPN users who access corporate messaging systems on a regular basis, Whale's technology is definitely worth a look.