Slam Dunk Networks and Tumbleweed Communications Combine to Deliver Messaging and Software Support for VeriSign's Secure Messaging Solution

REDWOOD CITY, CA - March 18, 2002 - In a recent announcement, VeriSign Inc. unveiled a new secure messaging and document delivery solution, SecureExpressSM, developed in partnership with Slam Dunk Networks. Available now, VeriSign's SecureExpress messaging service uses VeriSign's authentication and encryption components and is supported by messaging technology from Slam Dunk Networks and software from Tumbleweed® Communications Corp. (NASDAQ: TMWD).

By enabling businesses to reduce the risks associated with sending confidential information via the Internet, SecureExpress provides a protected, private channel in which subscribers digitally sign and encrypt messages and their attachments. The latest in VeriSign's suite of secure messaging services, SecureExpress employs VeriSign's industry-leading authentication services, including its managed PKI services, digital signature, encryption and roaming technologies. With SecureExpress, businesses and individuals use the strengths of the Internet to reduce the paper-based, delivery, tracking and administrative costs associated with traditional express message services. Moreover, users can send and receive messages confidently from their desktop, portable laptop, or home computer with far greater security than is available in the physical world.

Slam Dunk Networks provides and operates a managed network service that helps consumers and enterprises access VeriSign's SecureExpress service. "We are proud to provide the secure networking capabilities used to help support SecureExpress," said Bob Miller, founder and CEO of Slam Dunk Networks. "By using Slam Dunk's Network to support VeriSign's SecureExpress service, Slam Dunk will help companies of all sizes exchange information in the most secure and reliable manner in the world."

VeriSign and Slam Dunk selected Tumbleweed's Secure Messenger platform for the SecureExpress service. User management features, such as the inputting and compiling of data and documents with the VeriSign Personal Trust Agent for security, are also based on Tumbleweed's Secure Messenger. "We recommend SecureExpress as the natural, preferred outsource solution for our customers," said Jeff Smith, Chairman and CEO of Tumbleweed. "By combining VeriSign's industry-leading authentication services, including its managed PKI services, digital signature, encryption, and roaming technologies, our messaging software and Slam Dunk's networking capabilities, VeriSign's SecureExpress delivers best-of-breed messaging technologies to answer a widespread need for businesses in the area of secure messaging."

The SecureExpress service is available at http://secureexpress.verisign.com where customers may enroll in the service directly, learn more about how to send and receive secure messages, and contact VeriSign with other questions. Full membership allows subscribers to send and receive secure messages through SecureExpress. Receive-only membership allows subscribers to receive messages through SecureExpress. Receive-only membership is free. Prices are based on the number of seats (users) and represent only 20 percent of the costs of physical delivery systems while offering customers rapid, guaranteed delivery.

About Slam Dunk Networks
Slam Dunk Networks connects businesses for mission-critical transactions anywhere in the world through its global network. No other option including leased lines, VANs, or private networks can compete against Slam Dunk's combination of 100% availability, rapid deployment, immediate ROI, superior performance, and fully managed security. This managed network service is so powerful that Slam Dunk Networks guarantees delivery and tracking of all transaction messages. Founded in December 1998, Slam Dunk Networks is a privately held company with corporate headquarters in Redwood City, California. For more information visit: www.slamdunknetworks.com.

About VeriSign
VeriSign, Inc. is the leading provider of digital trust services that enable everyone, everywhere to engage in commerce and communications with confidence. VeriSign's digital trust services create a trusted environment through three core offerings- name, security and transaction services - powered by a global infrastructure that manages more than 5 billion network connections and transactions a day. Additional news and information about the company is available at www.verisign.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, Chevron, Datek Online, the European Union's Joint Research Council, First Union Wachovia, John Deere, Merrill Lynch, Nike, Northern Trust, NTT, Salomon Smith Barney, Travelers and US Food and Drug Administration. One hundred of the Fortune 500 are Tumbleweed customers. Tumbleweed Communications was founded in 1993 and is headquartered in Redwood City, Calif., with offices around the world.

Statements in this announcement other than historical data and information constitute forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. These statements involve risks and uncertainties that could cause VeriSign's actual results to differ materially from those stated or implied by such forward-looking statements. The potential risks and uncertainties include, among others: VeriSign's limited operating history under its current business structure; the risk that the VeriSign and its acquired businesses will not be integrated successfully and unanticipated costs of such integration; uncertainty of future revenue and profitability and potential fluctuations in quarterly operating results; failure of the combined company to retain and hire key executives, technical personnel and other employees; failure of the combined company to manage its growth and the difficulty of successfully managing a larger, more geographically dispersed organization; failure of the combined company to successfully manage relationships with customers, suppliers and strategic customers; network outages, network capacity constraints or security breaches; failure of the combined company's customers to accept new services or to continue using the products and services of the combined company; and competition in the various markets serviced by the combined company. More information about potential factors that could affect the company's business and financial results is included in VeriSign's filings with the Securities and Exchange Commission, especially in the company's Annual Report on Form 10-K for the year ended December 31, 2001. VeriSign undertakes no obligation to update any of the forward-looking statements after the date of this press release.

VeriSign is a registered trademark of VeriSign, Inc. Other names may be trademarks of their respective owners.