Tumbleweed's MMS Awarded the Federal Government's Security Certification (FIPS 140-1)

MMS Awarded Security Standard FIPS 140-1 Validation for Encryption Software

REDWOOD CITY, CA - June 20, 2001 - Tumbleweed® Communications Corp. (Nasdaq:TMWD), leading provider of mission-critical messaging software, announced today that Tumbleweed's Messaging Management System™ (MMS™) software was awarded the FIPS 140-1 validation for encryption software. FIPS 140-1 is the United States Federal standard for the validation of cryptographic systems to protect commercial or sensitive data. Now MMS provides government agencies and enterprises the FIPS 140-1 certification requirements necessary to securely communicate with other federal organizations, partners and customers.

"Tumbleweed's expertise in high security cryptographic solutions is clearly exemplified with the FIPS 140-1 certification by NIST," said Paul Hoffman, Director of Internet Mail Consortium. "This achievement underscores a trusted platform not only for Federal Agencies who require FIPS 140-1 validation, but for any enterprise that wants to protect its email communications infrastructure."

Tumbleweed MMS is a suite of software designed to allow organizations to apply security beyond the firewall and secure email and Web traffic. MMS provides a complete set of secure email solutions, including virus scanning, content control, access control, encryption, and authentication. MMS integrates with existing email networks and provides security for business communications using strong cryptography as a part of the S/MIME protocol.

"FIPS 140-1 certification from NIST gives our products an important stamp of approval not only for government but also commercial users," said Blake Ramsdell, Chief Cryptographer and Senior Architect of MMS, Tumbleweed Communications Corp. "This certification, in combination with our secure messaging expertise provides organizations with a trusted system to protect and enable email communications outside their enterprise."

Background of FIPS PUB 140-1: The Federal Information Processing Standard (FIPS) 140-1 provides a way of validating cryptographic products. It was produced by the U.S. National Institute of Standards and Technology (NIST) and adopted by the Communications Security Establishment (CSE) of the Government of Canada to lay out general requirements for cryptographic modules within computer and telecommunication systems. The FIPS PUB 140-1 Security requirements cover 11 areas related to the design and implementation of a cryptomodule.

About Tumbleweed
Tumbleweed Communications (NASDAQ: TMWD) is a leading provider of mission critical messaging software that enables organizations to manage and secure online business communications and processes. Tumbleweed's customers use the company's solutions to define secure communication networks, to centrally control and monitor the corporate communications stream and to create a foundation for automated preparation and secure Internet delivery of sensitive business information. Companies that rely on Tumbleweed Communications solutions include American Express, Chase Manhattan Bank, Chevron, Datek Online, the European Union's Joint Research Council, FDA, 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. More information can be found at www.tumbleweed.com.

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.