Tumbleweed Unveils Integrated Messaging Exchange™ 4.0

LOS ANGELES, CA - April 5, 2000 - Tumbleweed® Communications Corp. (Nasdaq:TMWD), a leading provider of secure Internet communications services, today announced Tumbleweed Integrated Messaging ExchangeT 4.0. IME 4.0 is Tumbleweed's newest set of products and services to leverage the Internet and existing email to create a secure online communications channel between e-businesses and their customers and partners.

"We are bringing IME 4.0 to the market as email, long a ubiquitous communications channel, is increasingly recognized as the foundation for online business. Email is the critical connection between e-businesses and their customers," said Jeffrey C. Smith, chairman, president and CEO, Tumbleweed Communications Corp. "Our customers make strategic investments in technologies that help them build and maintain strong relationships with their own customers. IME 4.0 was designed with the requirements of major enterprises in mind - we've built a highly scalable, comprehensive infrastructure that brings secure online communications full circle."

IME 4.0 includes significant improvements for both senders and recipients of secure communication. For example, IME 4.0 includes Tumbleweed Secure Inbox™, a feature that enables e-businesses to create a protected repository for each customer to whom they send documents. A user with a Secure Inbox has a safe place to receive, store and manage confidential data, the means to securely reply to or forward documents they receive, and the ability to create and send their own secure documents via IME. Users can access their private Secure Inboxes via their existing email clients or web browsers. As is always the case with IME, end users require no new software to receive a secure message over the Internet via IME.

A comprehensive communications platform, Tumbleweed IME 4.0 also includes new features for senders of secure messages. With auto-enrollment, advanced policy controls and deeper message tracking capabilities, IME 4.0 provides the infrastructure to support the preparation and delivery of any type of business document online. IME 4.0 leverages a company's existing infrastructure and is easily integrated with back-end systems. It features a range of security options, including digital certificate integration, encryption, SSL and the industry's first web-based implementation of S/MIME, which shipped as part of IME 3.0.

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.