Tumbleweed Endorses Microsoft's Recently Announced Anti-Spam Strategy.

Business Editors/High-Tech Writers

REDWOOD CITY, Calif.--(BUSINESS WIRE)--Nov. 17, 2003

Microsoft Anti-Spam Announcement Opens the Market for Broad Email

Security and Hygiene Capabilities at the Perimeter of the Network

Tumbleweed(R) Communications Corp. (NASDAQ:TMWD), a leading provider of mission-critical Internet communications software products for enterprises, financial services, healthcare and government, announced today their endorsement of Microsoft's recently announced anti-spam strategy.

"We are pleased to see Microsoft respond to the spam epidemic," said Dave Jevans, Senior Vice President of Marketing for Tumbleweed Communications. "Improving the spam filtering capabilities of future releases of the Exchange 2003 email server will be helpful in the battle against spam, and will complement enterprises' primary email firewall defenses."

Email firewalls are the first line of defense for a growing variety of email threats, including viruses, worms, spam, phishing and email spoofing, and email denial of service attacks. Microsoft's multi-filter approach to fighting spam in future versions of their Exchange 2003 email server can make seamless integration with email firewalls easier, and potentially increase spam capture rates for enterprise customers.

"This announcement by Microsoft validates the need for strong email hygiene," said Matt Cain, Vice President of the META Group. "Spam is clearly today's most urgent email threat, but organizations need a set of technologies that also allow them to address numerous other threats to email system stability, security and productivity. In particular, emerging security problems such as phishing attacks, email spoofing, and email-borne worms are pushing organizations to include content filtering, digital signing, and email encryption technologies as part of their email hygiene arsenal."

The Tumbleweed MMS(TM) email firewall fulfills this role by providing best-of-breed anti-spam filtering at the Internet gateway, as well as integrated anti-virus, inbound and outbound content filtering, digital signing, and email encryption. Digitally signed email is increasingly important in the fight against email spoofing scams and password phishing attacks. These email hygiene capabilities, in combination with encrypted email, are also highly effective for regulatory compliance with HIPAA, GLB and other email privacy regulations.

About Tumbleweed's Email Firewall and Message Protection Lab

The Tumbleweed MMS Email Firewall has been recognized as a top rated enterprise software solution for fighting spam according to Network World (http://www.nwfusion.com/reviews/2003/0915spam.html), and the #1 email firewall software for large enterprises by Information Security Magazine. MMS protects inbound and outbound email traffic at the network perimeter with an integrated set of anti-spam, anti-virus, anti-hacker, content filtering, email relay, and encrypted messaging capabilities, minimizing email communications risks and reducing email management costs. MMS is used in hundreds of the largest, most demanding enterprise email infrastructures in the world, and is available in both hardware appliance and software editions.

The Tumbleweed Message Protection Lab is staffed 24 hours a day by experts who continually analyze email threats, and publish over 500 new spam, scam and virus defense updates daily via Tumbleweed's unique Dynamic Anti-spam Service. The Dynamic Anti-spam Service is an Internet-based subscription service that integrates with MMS, and allows Tumbleweed customers to download new anti-spam heuristics that are published up to six times per day. By analyzing both spam and legitimate email gathered from worldwide sources (including Tumbleweed's enterprise customers), the Message Protection Lab helps minimize "false positives" -- legitimate email that gets stuck in traditional heuristics-based spam filters. Minimizing false positives is critical when email is used for important business communications. And by automating the process of spam, scam and virus analysis and blocking, the Message Protection Lab and Dynamic Anti-spam Service allow Tumbleweed customers to spend their time on other critical email management problems.

"This announcement by Microsoft is a major positive step in helping to control the growth of spam," said Sara Radicati, President and CEO of market research firm The Radicati Group. "Dealing effectively with spam is a very complex issue and requires a multi-level approach, similar to the anti-virus model, which includes best-of-breed components as well as a corporate-wide strategy for managing the multiple threats that spam poses. This remains a very large market with plenty of opportunity for a variety of vendors."

About Tumbleweed Communications Corp.

Tumbleweed is a leading provider of mission-critical Internet communications software products for enterprises, financial services, healthcare and government. By making Internet communications secure, reliable and automated, Tumbleweed's anti-spam email firewall, secure file transfer, secure email, and identity validation solutions help customers significantly reduce the cost of doing business. Tumbleweed products are used to communicate with millions of end-users and tens of thousands of corporations. Tumbleweed has more than 600 enterprise customers, including ABN Amro, Bank of America Securities, Catholic Healthcare West, JP Morgan Chase & Co., The Regence Group (Blue Cross/Blue Shield), Society for Worldwide Interbank Financial Telecommunication (SWIFT), St. Luke's Episcopal Healthcare System, the US Food and Drug Administration, and the US Navy and Marine Corps. Tumbleweed Communications was founded in 1993 and is headquartered in Redwood City, California. For additional information about Tumbleweed go to www.tumbleweed.com or call 650-216-2000.

SAFE HARBOR STATEMENT

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 features and performance characteristics of Tumbleweed's anti-spam products and services. 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 June 4, 2003 and Form 10-Q filed November 14, 2003.

Tumbleweed assumes no obligation to update information contained in this press release, including for example its guidance regarding its future performance, which represents the Company's expectations only as of the date of this release and should not be viewed as a statement about the Company's expectations after such date. Although this release may remain available on the Company's website or elsewhere, its continued availability does not indicate that the Company is reaffirming or confirming any of the information contained herein.