InstallShield Fights Spam With Tumbleweed's Dynamic Anti-Spam Service.

Business Editors/High-Tech Writers

REDWOOD CITY, Calif.--(BUSINESS WIRE)--Aug. 25, 2003

InstallShield Deploys Tumbleweed's Anti-Spam Service

Into Their E-Mail Firewall Gateway to Protect Corporate E-Mail

Tumbleweed(R) Communications Corp. (Nasdaq:TMWD), a leading provider of mission-critical Internet communications software for enterprises, financial services organizations and government, announced today that InstallShield Software Corp., the market leader in software installation products, has deployed Tumbleweed's Dynamic Anti-Spam Service(TM) (DAS) as part of their e-mail firewall, eliminating nearly all spam coming into the organization literally overnight.

"We tested the Dynamic Anti-spam Service on a Friday evening, and on Saturday our mail flow was down so much, I worried the e-mail servers were down," said Conal Gallagher, Director of Systems, InstallShield Software Corporation. "Instead, it was just that the spam had gone away. DAS does an incredible job of filtering out the spam coming in to our company, and with the automated update service, it requires little to no maintenance."

InstallShield has been using the Tumbleweed MMS e-mail firewall for over three years to provide anti-virus protection at the Internet gateway, intelligent filtering and routing of e-mail based on content, and SMTP relay services. InstallShield receives over 10,000 e-mail messages per day for its 200 employees, with over 50% of that volume considered spam. Some employees were receiving over 300 spam messages per day, and it was becoming a severe problem.

"Firms like InstallShield have struggled with the growing spam problem -- today one of the biggest issues faced by IT staff," said Dave Jevans, Senior Vice President of Marketing for Tumbleweed Communications. "InstallShield has realized the benefits of a centrally managed and integrated approach to proactively protecting their mission-critical e-mail stream."

About Tumbleweed's Dynamic Anti-Spam Service

The Tumbleweed Dynamic Anti-spam Service is an Internet-based subscription service that updates the Tumbleweed MMS e-mail firewall with new heuristic defenses as they are published, similar to the way anti-virus engines work. The e-mail firewall includes a highly effective Spam Analysis Engine, which automates the identification of spam using powerful heuristics-based analysis technology; typical customers see an immediate 90%+ capture rate with one-tenth of one percent false positive rate before tuning. Tumbleweed's Message Protection Lab develops and publishes the heuristic updates: the Lab is staffed by experts who continually analyze spam to identify new spammer trends and tactics, and create and publish new heuristics to stop them. The Lab analyzes both spam and legitimate e-mail gathered internationally and provided by enterprise customers, to ensure that the Dynamic Anti-spam Service minimizes false positives in a business environment.

About Tumbleweed's MMS e-Mail Firewall

The Tumbleweed MMS(TM) e-mail firewall is rated by Information Security Magazine as the #1 e-mail firewall software for large enterprises, and is currently in use at over 400 of the largest, most demanding messaging infrastructures in the world. Tumbleweed MMS is an enterprise-class e-mail firewall for protecting, filtering and securing e-mail traffic at the Internet gateway. MMS manages the organization's mission-critical e-mail stream with an integrated set of anti-spam, anti-virus, anti-hacker, content filtering, e-mail relay, and encrypted messaging capabilities -- minimizing e-mail communications risks and reducing e-mail management costs.

Organizations use MMS to protect their networks from hacker, virus and spam threats; comply with e-mail regulations (SEC, NASD, HIPAA, GLB, FDA); enforce e-mail communications and security policies; and securely communicate with customers, partners and suppliers. Tumbleweed MMS complements and works seamlessly with corporate e-mail servers such as Microsoft Exchange, Lotus Notes, Novell Groupwise and a variety of UNIX-based e-mail servers. The product is available as both a software package for larger companies, or as an appliance that provides enterprise level protection and management capabilities to small and mid-sized companies.

About InstallShield

InstallShield Software Corp. is the acknowledged leader in software installation, deployment packaging, and updating solutions. The company offers a wide range of products and services that guarantee the successful distribution, management and set up of applications for independent software vendors, systems administrators and end users. InstallShield was founded in 1987, and is headquartered near Chicago in Schaumburg, Ill., with European headquarters in Bristol, England. For more information, visit www.installshield.com.

About Tumbleweed Communications

Tumbleweed is a leading provider of mission-critical Internet communications software products for enterprises, financial services organizations and government. By making Internet communications secure, reliable and automated, Tumbleweed's e-mail firewall, secure file transfer, secure e-mail, and identity validation solutions help customers significantly reduce the cost of doing business. Tumbleweed products are used by millions of end-users and tens of thousands of corporations. Tumbleweed customers include ABN Amro, Bank of America Securities, Catholic Healthcare West, JP Morgan Chase & Co., The Regence Group (Blue Cross/Blue Shield), Society for Worldwide Interbank Financial Telecommunication (SWIFT), St. Luke's Episcopal Healthcare System, the US Food and Drug Administration, and the US Navy and Marine Corps. Tumbleweed Communications was founded in 1993 and is headquartered in Redwood City, Calif. For additional information about Tumbleweed go to www.tumbleweed.com or call 650-216-2000.

SAFE HARBOR STATEMENT

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 effectiveness of Tumbleweed's products and services and the potential benefits of those products in commercial use. 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 Annual Report on Form 10-K filed June 4, 2003, and Quarterly Report on Form 10-Q filed August 14, 2003.

Tumbleweed assumes no obligation to update information contained in this press release, which represents the Company's expectations only as of the date of this release and should not be viewed as a statement about the Company's expectations after such date. Although this release may remain available on the Company's website or elsewhere, its continued availability does not indicate that the Company is reaffirming or confirming any of the information contained herein.