GULF BREEZE, Fla., Nov. 27, 2006 – AppRiver LLC, a leading supplier of business email security solutions, today announced an agreement to supply its SecureTide™ spam and virus detection technology to Rackspace Managed Hosting™, a recognized leader in the global managed hosting market.

Under the agreement, Rackspace will deploy the powerful solution that uses more than 60 types of filtering techniques to rid incoming email of worms, viruses, phishing attempts and other protocol-based vulnerabilities to add a critical security layer to its Managed Microsoft Exchange, the latest addition to Rackspace’s comprehensive email solution portfolio.

SecureTide also provides perimeter security to protect from a myriad of attacks, including Denial of Service (DOS) and Directory Harvesting, and reduces bandwidth consumption and mailbox clutter, ensuing improved efficiency and system performance for Rackspace customers.

“We are excited to be deployed as a critical element of Rackspace’s newest service,” said Scott Cutler, AppRiver’s executive vice president. “Rackspace is a worldwide leader in meeting the most critical needs of businesses for IT infrastructure and application availability. To be chosen as part of their Exchange Hosting is a strong endorsement of our email security technology.”

Offering companies of all sizes an on-demand and highly available implementation of Microsoft’s popular email and collaboration solution, Managed Microsoft Exchange from Rackspace includes advanced email with shared calendars, contact lists, public folders and task management features to enhance individual and team productivity. The fully-managed service approach transforms Microsoft Exchange Server 2003 into a simple and scalable service in which customers only pay for the mailboxes they plan to use.

“Our relationship with AppRiver enables us to deliver spam and antivirus protection as an all-inclusive feature to every customer utilizing Managed Microsoft Exchange from Rackspace,” said Emil Sayegh, director, Product Marketing, Rackspace Managed Hosting. “AppRiver’s SecureTide is a key part of our comprehensive security strategy to better protect our Managed Exchange customers. The company not only offers some of the best email spam and antivirus protection available, but they share in our customer service philosophy which has made our Fanatical Support™ renowned throughout our industry.”

After completing a successful beta test of Managed Microsoft Exchange from Rackspace with positive customer feedback, the company is now hosting thousands of mailboxes for hundreds of customers around the world who entrust the company to manage their mission-critical email functions.

About Rackspace Managed Hosting

A recognized leader in the global managed hosting market, Rackspace Managed Hosting is a world-class service organization delivering enterprise-level Web infrastructure and managed services to businesses of all sizes. Serving more than 10,000 customers across seven data centers worldwide, Rackspace integrates the industry’s best technologies for each customer need and delivers it as a service via the company’s award-winning Fanatical Support™. Through trusted relationships with its customers, Rackspace serves as an extension of their IT department, enabling customers to focus on their core business. Founded in 1998, Rackspace has grown more than 50 percent a year since the company’s inception. For more information, please visit www.rackspace.com, or call 800-961-2888.

About AppRiver

AppRiver is a privately held provider of business email solutions, with more than 8,000 customers using its managed services and over 25,500 businesses worldwide using its security solutions. Founded in 2002, the Gulf Breeze, Florida-based company maintains multiple Tier 1 data centers at secure locations in the United States and Europe. Additional information about AppRiver is available at www.appriver.com.