Press Release

POSTINI POSITIONED IN LEADERS QUADRANT FOR LEADING INDEPENDENT ANALYST FIRM'S MAGIC QUADRANT

Evaluation Based on Completeness of Vision and Ability to Execute

SAN CARLOS, CA, September 27, 2006 — Postini, the industry's leading provider of on-demand Integrated Message Management services that make electronic communications like e-mail, instant messaging (IM) and the web more compliant, productive, secure and reliable, today announced that it has been placed in the Leaders Quadrant in Gartner's "Magic Quadrant for E-mail Security Boundary, 2006."ⁱ According to Gartner, Inc. "Leaders are performing well today, have a clear vision of market direction and are actively seeking competencies to sustain their leadership position in the market."

In the new magic quadrant report, Gartner, Inc. said that while software products dominate the installed base, they see a rapid decline in interest in software products in favor of appliances and service provider offerings. The analyst firm also said that prescient organizations should be looking for a suite-based approach with integration of IM and other web-based communications on the front end and intelligent archiving integration on the back end. What buyers need to look for in vendors are integrated communication such as manageability, outbound content filtering, encryption, instant messaging and web integration, and archiving integration. In addition, the analyst firm said efficient and accurate spam and virus filtering with low administration overhead remains essential to buyers.

According to Gartner, Inc., the pending converged communications market represents a huge opportunity for e-mail solutions vendors to elevate their status in the organization by providing policy and protection services across multiple communications media.

"As electronic communications become ever more mission critical to businesses worldwide, Postini is delighted to be evaluated by Gartner in this important new magic quadrant report," said Quentin Gallivan, president and CEO of Postini. "We're seeing a dramatic market evolution. Postini and the more than 36,000 businesses that use our services have been driving the shift away from expensive and limited premises software to on-demand Software-as-a-Service solutions, and the need to deliver and deploy integrated suites instead of point technologies."

Gartner, Inc. said they continue to see broad interest in service provider offerings by all of their clients, and that globally. Moreover, the market is growing at approximately 40 percent.

The Completeness of Vision score was heavily weighted by two major categories: market understanding and product offering. Gartner, Inc. evaluated a vendor's market understanding by how closely their current and past vision of the market aligns with Gartner clients' "pain points" and needs and Gartner's analysis of the market's future. Gartner placed the most weight on product offerings and scored vendors in seven functional categories:

• Manageability
• Spam and Antivirus Effectiveness
• MTA Capabilities
• Outbound Content Filtering
• Encryption
• IM & Web Channels
• Archiving Integration

In terms of manageability, Gartner, Inc. evaluated the ability of end users to lower administration overhead exploiting such features as intuitive management interface, end-user quarantine areas and controls, delegated administration of solution components, customizable reporting, real-time dashboards, and troubleshooting tools (such as tracking lost messages, finding filters responsible for false positives, etc.). For spam and antivirus effectiveness, more credit was given to vendors that had their own evolving filtering cocktail approach. Gartner, Inc. also valued integrated email encryption into a product such that it is transparent to end users and easy for administrators to set up and troubleshoot. Credit was also given to companies that have demonstrated a good track record of innovative features and/or patents relative to e-mail security.

About the Magic Quadrant
The Magic Quadrant is copyrighted September 25, 2006 by Gartner, Inc. and is reused with permission. The Magic Quadrant is a graphical representation of a marketplace at and for a specific time period. It depicts Gartner's analysis of how certain vendors measure against criteria for that marketplace, as defined by Gartner. Gartner does not endorse any vendor, product or service depicted in the Magic Quadrant, and does not advise technology users to select only those vendors placed in the "Leaders" quadrant. The Magic Quadrant is intended solely as a research tool, and is not meant to be a specific guide to action. Gartner disclaims all warranties, express or implied, with respect to this research, including any warranties of merchantability or fitness for a particular purpose.

About Postini
Postini is the global leader in integrated message management, providing more than 36,000 businesses worldwide with on-demand services that increase the compliance, productivity, security and reliability of electronic communications including email, instant messaging, and the Web. The company's suite of communications productivity and security services provide anti-spam, anti-virus, anti-phishing, and policy management. Postini's communications compliance and reliability solutions include email and instant messaging archiving and discovery, message encryption, and messaging continuity. With no software or hardware to install, maintain, or upgrade, Postini clients save as much as 90% over alternatives while enjoying 99.999% availability and award-winning 24x7 support. For more information please contact Postini at info@postini.com or visit http://www.postini.com.

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ⁱ Gartner Research "Magic Quadrant for E-mail Security Boundary, 2006" by P. Firstbrook and A. Hallawell. September 25, 2006