It seems everyone who's anyone in the e-mail security world is getting into the appliance business.

As Sendmail's product announcement this week illustrates, appliances that sit at the gateway are becoming a popular way for companies to guard against e-mail threats while performing an array of other services, such as instituting corporate and regulatory policies, encrypting sensitive e-mail and preventing intellectual property from leaving the company. Sendmail joins a long list of vendors in this market; some such as Symantec and Proofpoint are relative newcomers, while others, including IronPort and BorderWare, have been promoting the appliance approach for years.

Sendmail's Sentrion e-mail gateway appliance, slated for release in early October, takes the features of the company's Mailstream Manager gateway software and makes them available on a high-performance, secured appliance, says John Ore, Sendmail's director of product marketing. As with many other products in this area, Sentrion's modules include spam and virus protection, connection control that throttles back messages deemed suspect, policy implementation designed to keep communications in line with regulations and corporate mandates, and the archiving and encrypting of messages. These can all be administered from a Web interface, Ore says.

"This is just really easy to set up and get going, even if you're not an e-mail expert," says Tim Boyer, director of IT at manufacturer Denman Tire, which is beta testing Sendmail's Sentrion. "And now I have a single place where I can put all my [e-mail] policies in place."

That's not to say other approaches to e-mail security are going away. Very large organizations prefer to get their e-mail security in software form so they can customize it to their specific needs, while smaller companies like the no-fuss approach of managed e-mail services, says Matt Cain, an analyst at Gartner.

Many vendors are competing on multiple fronts. Symantec offers e-mail security as a software, service, or via an appliance; CipherTrust sells its IronMail appliance but also offers to host it for companies; and a number of companies, including MailFrontier, Mirapoint, Proofpoint, SurfControl and Tumbleweed, sell both gateway software and appliances. The purists in this market include the companies that offer hosted services, such as Postini and FrontBridge, which was acquired by Microsoft this summer.