Cable & Wireless HKT and Hongkong Post Join Hands to Launch Hong Kong's First e-Cert Application Service

Websenger - PKI-enabled Secure Digital Delivery Service based on Tumbleweed IME

REDWOOD CITY, CA - May 17, 2000 - Tumbleweed® Communications Corp. (Nasdaq:TMWD), Cable & Wireless HKT and Hongkong Post today have jointly announced the launch of Websenger, Hong Kong's first commercial e-Cert application service. The new service is tailored to meet critical requirements of businesses and professional bodies for secure on-line communication and cost-effective delivery of important documents over the Internet.

Websenger secure digital delivery service is the first in Hong Kong to offer multi-level email messaging security, providing users with total control and privacy in message delivery via the Internet.

Websenger currently offers three levels of security - Secured Socket Layer (SSL) connection, password-based authentication and Hong Kong's first e-Cert-based end-to-end encryption. The new service is also PKI (Public Key Infrastructure) - enabled, allowing users to digitally sign and encrypt messages using their personal private key and the designated recipient's public key. In addition, comprehensive tracking records are maintained to provide detailed information on sending/receiving date and time.

Norman Yuen, Deputy Chief Executive of Cable & Wireless HKT, says "Today's launch of Websenger signifies a close cooperation between Hongkong Post and us to build a reliable e-Business infrastructure for secure data exchange over the Internet. With a vision to expedite e-Commerce development in Hong Kong and the Asia-Pacific region, we are committed to developing and providing e-Cert and PKI-enabled total solutions and services for both business-to-business (B2B) and business-to-consumers (B2C) sectors."

Postmaster General P C Luk, JP says, "With the launch of Websenger, we aim to better meet the requirements of local businesses and industries for secure on-line communication and cost-effective transmission of critical messages and time-sensitive documents. Websenger together with the Hongkong Post Certification Authority (CA) services and other upcoming PKI applications will help Hong Kong maintain its competitive edge in today's e-Commerce world and give added impetus to the overall economic growth of the SAR."

Mr Yuen adds, "We are very encouraged by the support given to the new Websenger secure digital delivery service by trial customers, such as CLP Power Hong Kong Limited, Deloitte Touche Tohmatsu and Hong Kong Productivity Council. We are confident that more users will quickly come to appreciate the added security benefits and total control that Websenger offers."

Powered by Tumbleweed Integrated Messaging Exchange™ (IME™), a product of Tumbleweed Communications Corp. [NASDAQ: TMWD], a leading provider of secure Internet communications services, Websenger offers advanced service features, such as Message Tracking, Scheduled Delivery and Auto Message Cancellation. Users will be able to conveniently track the status of sent messages and deliver time-specific messages within a pre-set time frame. They will also have the flexibility to cancel any sent message after a pre-set duration or before it is open by the recipient. Websenger also marks a new page in courier service development, enabling businesses to exchange digital files of product samples as attachments. (For details on the business application of Websenger service, please visit https://www.websenger.com.)

Cable & Wireless HKT
Cable & Wireless HKT, a Cable & Wireless company, is Hong Kong's major full-service communications provider, marketing a full array of quality voice and data telecommunication services backed by a state-of-the-art, fully digital fibre-optic network. Services include basic telephony, mobile telephony, international calls, specialized fax and data products, value-added services, Internet access, multimedia services, satellite links and telecommunications equipment and systems.

The outstanding quality of Cable & Wireless HKT's services was recognised in the global award of "Most Competitive Local or National Carrier" conferred in the Financial Times Global Telecommunications Awards in October 1999. Additionally, in a survey conducted by CFO Asia in November 1999, Cable & Wireless HKT was named as the number one company in Asia based on the wealth it has created for shareholders.

Apart from owning and operating Asia's largest commercial teleport, Cable & Wireless HKT is a pioneer in a wide range of communications solutions, such as launching the world's first fully digitized urban network, the world's first fibre-optic cable linking China, and the world's first interactive television services.

Cable & Wireless HKT has formed an Integrated eBusiness Solutions (IBS) unit to spearhead e-business development in Hong Kong and the Asia-Pacific region via six key streams of business, namely Business Solutions for eCommerce, Data Centre Services, eCommerce, Business Portals, ASP (Application Service Provider) and Fulfillment and Logistics Services.

Hongkong Post
To enable the development of electronic commerce in Hong Kong, Hongkong Post has established a public key infrastructure (PKI) and acts as the first public Certification Authority (CA) in Hong Kong on 31 January 2000.

As empowered by S34 of the Electronic Transaction Ordinance (ETO), Postmaster General is a recognised certification authority in Hong Kong. Hongkong Post issues digital certificates, namely Hongkong Post e-Cert to individuals and businesses to authenticate the identity of the subscribers over the Internet. Hongkong Post issues four types of e-Cert, namely Personal; Organisational; Encipherment and Server Certificates. As well, Hongkong Post CA maintains a certificate repository and directory to allow the public to verify the validity of a particular Hongkong Post e-Cert prior to carrying out transactions. These services provide a secure and trusted environment for the conduct of electronic commerce in Hong Kong.

Hongkong Post e-Cert may be used to perform commercial operations and can enable safe and secure electronic transactions in the field of banking, finance, telecommunications, entertainment, education and health etc. Hongkong Post e-Cert will also support the Government's Electronic Service Delivery (ESD) scheme, which will be available by late 2000.

About Tumbleweed Communications Corp.
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.

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.