Press Release

POSTINI MESSAGE SECURITY AND MANAGEMENT UPDATE FOR OCTOBER REVEALS THAT SPAM IS BACK WITH A VENGEANCE

Spam Skyrockets 59 Percent September to November; 91 Percent of All Email is Now Spam

SAN CARLOS, CA, November 6, 2006 – Postini, the industry's leading provider of on-demand Integrated Message Management services making electronic communications like email, instant messaging (IM) and the web more compliant, productive, secure and reliable, today announced that spammers are out in full force, severely threatening corporate networks while seeking financial gain. Postini processed nearly 70 billion email connections from September to November, and saw a 59 percent spike in spam over that period. Unwanted email is currently 91 percent of all email, and over the past 12 months the daily volume of spam rose by 120 percent. Postini also saw a dramatic increase in overall email traffic with 10 billion more connections in October than in September.

"This dramatic rise in spam attacks on corporate networks has the Internet under a state of siege," said Daniel Druker, executive vice president of marketing at Postini. "Spammers are increasingly aggressive and sophisticated in their techniques, and protection from spam has become a front-burner issue again. Spam has evolved from a tool for nuisance hackers and annoying marketers to one for criminal enterprises."

Spammers now use massive networks of hijacked computers called "bot-nets" to initiate attacks. The attacks are aggressive – Postini tracks more than one million infected computers that are coordinating spam and virus attacks each day, with 50,000 or more active at any instant.

Spammers are also continuously evolving their tactics. Image spam and MS Office document spam now makes up as much as 30 percent of all junk messages, up from two percent in 2005. Hackers now use techniques such as re-arranging as many as 25 tiny images into a message in an HTML email or using animated GIF attachments to bypass optical character recognition technology in an effort to bypass email security systems. Infected computers are now also re-trying temporarily blocked email connections just like real mail servers do.

Postini's PREEMPT™ multi-layer anti-virus technology also blocked over 31 million viruses for October. The Stration virus, also known as Warezov, was particularly active and aggressive in October. This trojan virus is designed to take over target computers, harvest email addresses and turn infected computers into spam-spewing robots.

The top five viruses for October were:

Virus Name	Quantity Blocked
stration	6,482,308
netsky	5,524,450
mytob	2,784,030
mime	2,524,038
mydoom	1,525,975

Postini's StatTrak™ is available at www.postini.com/stats and provides the most up-to-date statistics on the latest viruses, spam and DHAs.

About Postini
Postini is the global leader in Integrated Message Management, providing compliance, security, availability, and visibility solutions for corporate email, instant messaging and web. Postini offers a complete suite of on-demand services including archiving, spam and virus blocking, content control, encryption, and business continuity. The company's powerful managed services infrastructure seamlessly integrates with customers' environment, providing uncompromising security for more companies than any other provider in the world. Postini's services protect organizations from a wide range of threats, reduce compliance and legal risks, ensure reliable communications, and enable the intelligent management and enforcement of enterprise policies that protect companies' intellectual property, reputations and business relationships. For more information please contact Postini at info@postini.com or visit http://www.postini.com.