Canada Post First to Launch PosteCS™ on Tumbleweed IME™

New allowance the sixth patent for Tumbleweed secure communications technologies

REDWOOD CITY, CA - April 28, 2000 - Tumbleweed® Communications Corp. (Nasdaq:TMWD), a leading provider of Internet communications services, announced that Canada Post is the first postal service to launch the secure electronic delivery service PosteCS™ commercially using its Integrated Messaging ExchangeT (IMET).

PosteCS is built on Tumbleweed Integrated Messaging Exchange, a platform that leverages the Internet and existing email networks to create a secure online communications channel for e-businesses. PosteCS offers encryption, password protection, an Electronic Postmark™, universal format conversion (.pdf), delivery tracking, and the capability to import mail lists and set document expiration dates.

"With PosteCS, we're offering our customers a state-of-the-art communications solution that combines the most valuable features of traditional delivery methods with the immediacy and flexibility of electronic delivery," said Peter Melanson, vice-president, Electronic Services. "We are delighted that Tumbleweed IME forms the foundation of PosteCS. Using IME means that our customers have a highly secure document delivery service that works with the web browser and email software they already use. Anyone can securely send a document via PosteCS today - without adding any new software."

"It's tremendous to see Canada Post Corporation's PosteCS service available to every Canadian," said Jeffrey C. Smith, President and CEO, Tumbleweed Communications Corp. "Several of the world's largest postal services have licensed Tumbleweed IME, and Canada Post is the first to launch and deploy the service nationwide. The combination of PosteCS and the Electronic Postmark is a powerful communications tool for consumers and businesses in Canada and around the world."

Each year, Canada Post Corporation is entrusted with 9 billion messages and parcels. These materials are processed through 22 major plants and many other facilities for delivery to nearly 13 million addresses in Canada. There are more than 18,600 retail points of purchase where customers can access postal services. Canada Post is the fifth largest employer in the country and has commercial, operational, and financial links with over 200 postal administrations around the world.

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.