KPN Integrates Tumbleweed's Security Software in its Messaging-Services

REDWOOD CITY, CA - July 24, 2001 - KPN Enterprise Solutions Netherlands extends its messaging-services with security software from Tumbleweed® Communications Corp. (NASDAQ:TMWD), a leading provider of secure content management solutions for enabling the business Internet. Customers using KPN services are primarily large organizations and government institutions.

KPN is using Tumbleweed Messaging Management System™ (MMS™). Tumbleweed MMS is used to secure all email communications using S/MIME encryption. This allows KPN customers to profit from a secure communication channel leveraging the Internet's reach, at a fraction of the costs of a traditional secure line (virtual private network).

Martin Maurits, director of KPN Enterprise Solutions Nederland, "Our customers increasingly demand the highest quality of security for their messaging traffic. Using Tumbleweed's technology, KPN ESN can comply with their demands. Functionalities that KPN ESN offers include: automatically appending disclaimers to email, extensive encryption services and content filter functionalities."

"Tumbleweed's technology offers a secure and trackable communications network, based on existing IT infrastructure and on IT standards. Our customers know that they can rely on us and on our products, so that they can focus on building their own (online) services," says Arien Klomp, Country Manager Benelux.

About KPN ESN
All actual and historical press information of KPN and her subsidiaries can be found in the digital pressroom at www.KPN.com.

About Tumbleweed
Tumbleweed is a leading provider of secure content management solutions for managing 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 over 1,000 blue-chip customers including American Express, JP Morgan Chase & Co., Chevron, Datek Online, the European Union's Joint Research Council, Federal Drug Administration, John Deere, Merrill Lynch, Nike, Northern Trust, NTT, Salomon Smith Barney, Travelers, United Parcel Service, and seven of the world's largest postal services. Tumbleweed Communications was founded in 1993 and is headquartered in Redwood City, CA 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.