Tumbleweed Solution for Secure Mail Protects InstallShield Software Against SirCam Virus

Tumbleweed's secure policy gateway prevents viruses and denial-of-service attacks before they can enter InstallShield's network environment

REDWOOD CITY, CA - August 29, 2001 - Tumbleweed® Communications Corp. (Nasdaq:TMWD), a leading provider of secure content management solutions for enabling the business Internet, today announced that it has already begun to save time and money for its new customer, InstallShield, Software Corp., the acknowledged leader in Internet-enabled software distribution and installation deployment solutions. Although InstallShield deployed Tumbleweed's Messaging Management System only recently, the company is already achieving a return on their investment, including the protection of their networks from email virus attacks and an increase in productivity and network performance. InstallShield, which deployed the Tumbleweed solution to monitor and manage the email communication stream with its customers and partners on the Internet, reported that Tumbleweed software, which is installed at their gateway, stopped the SirCam virus before it could penetrate InstallShield's network. This saved the company from any corporate data loss and countless hours in damage control. Last month, the SirCam virus accounted for 65% of all reported virus infections.

Tumbleweed offers a comprehensive suite of secure mail, web, archive and secure content management products. Tumbleweed's secure mail solution enables InstallShield to protect valuable corporate information and protect communications leaving and entering their network. InstallShield, whose products enable the distribution, management, and consumption of software and digital content via the Internet and throughout the corporate enterprise, uses MMS to set policies to apply content control, encryption, access control, attachment management, virus scanning and digital signature policies that are administered centrally and universally across its enterprise.

"We implemented Tumbleweed MMS to manage our email communication stream because we needed a comprehensive solution that was scalable, easy to install and most of all, provided complete security across all key points of our enterprise," said Conal Gallagher, director of systems, InstallShield Software Corp. "Tumbleweed's MMS product has proven reliable and effective. Not only did it save us from untold hours of lost productivity by protecting us from the Sircam virus, it was easy to configure, maintain, and was completely transparent to our organization. We are operating with greater confidence now that we have a Tumbleweed solution in place to secure our business communications."

According to Jeffrey C. Smith, Chairman and CEO, Tumbleweed Communications Corp., "Every day, important business information is being exchanged among customers and business partners via Internet email. By integrating our software solutions with existing email networks, companies like InstallShield can apply content filtering, and spam and virus protection to reduce liability and protect valuable network and system resources."

About InstallShield Software Corp.
InstallShield Software Corp. is the acknowledged leader in software-distribution and installation-deployment solutions. InstallShield provides a full spectrum of products and services that enable the distribution, management, and consumption of software and digital content via the Internet and throughout the enterprise. Founded in 1987, the privately held, global company consistently is recognized as the authority in software deployment technologies, receiving over 50 industry awards for its products. Ranked by Media Metrix, Inc. as the sixth-most-frequently owned software solution for personal computers, InstallShield technology powers deployment for all of the top 100 independent software vendors and more than 100,000 corporate and commercial software developers and digital content providers worldwide. InstallShield's key customers and strategic partners include Adobe, Computer Associates Intl., IBM, Microsoft, and Sun Microsystems. InstallShield is headquartered outside of Chicago in Schaumburg, Ill. For more information, visit www.installshield.com.

About Tumbleweed
Tumbleweed is a leading provider of solutions for managing secure communication and collaboration to enable the business Internet. Tumbleweed's robust policy-based framework empowers organizations to safely share and protect critical information, increase customer loyalty and privacy and dramatically reduce costs. Tumbleweed is trusted by 1,000 blue-chip customers including American Express, JP Morgan Chase & Co., Chevron, Datek Online, the European Union's Joint Research Council, Food and Drug Administration, John Deere, Merrill Lynch, Nike, Northern Trust, NTT, Salomon Smith Barney, Travelers, United Parcel Service, and seven of the world's largest postal services. Tumbleweed Communications was founded in 1993 and is headquartered in Redwood City, CA with offices around the world.

Except for the historical information contained herein, the matters discussed in this press release may constitute forward-looking statements that involve risks and uncertainties that could cause actual results to differ materially from those projected, particularly with respect to the security features of Tumbleweed's products and the activities of any third party. In some cases, forward-looking statements can be identified by terminology such as "may," "will," "should," "potential," "continue," "expects," "anticipates," "intends," "plans," "believes," "estimates," and similar expressions. For further cautions about the risks of investing in Tumbleweed, we refer you to the documents Tumbleweed files from time to time with the Securities and Exchange Commission, particularly Tumbleweed's Form 10-K filed March 30, 2001 and Form 10-Q filed November 13, 2001. Tumbleweed assumes no obligation to update information contained in this press release.