Tumbleweed report highlights how stock-tip spam can have a negative impact

Redwood City, CA - Dec. 19, 2006 - Tumbleweed® Communications Corp. (NASDAQ:TMWD), providers of innovative messaging security solutions, today announced research findings on the correlation between waves of stock-tip spam and the short-term increase of stock trading volume and value. While tracking various types of spam to lead efforts in fighting spammers, Tumbleweed has observed the effects of "pump-and-dump" spamming scams seeking to inflate a penny stock's price for a quick profit. These scams, seeking to take advantage of investors, usually target over-the-counter (.OB) or pink sheet (.PK) stocks, which are high risk, loosely regulated and relatively inexpensive to trade.

According to Tumbleweed’s analysis of various stocks targeted by spammers during 2006, these scams temporarily inflated a stock’s value immediately following a spam wave.  A few days after the initial spam wave, however, the stock value  decreased to levels approaching their original value, and today’s average price for these same stocks is less that the initial stock price, prior to the first spam wave.

Tumbleweed’s Message Protection Lab (MPL) continually tracks new spam trends as it develops innovative techniques for blocking the latest spamming practices.  In 2006, the MPL has tracked a huge surge in spam volume with dramatic increases in stock-tip spam, much of it using images to mask content.

The lab tracked a sample of 15 spam waves with over 3,500 messages for these stocks throughout 2006 measuring spam volume, trading volume, and short-term and longer-term price changes.  This research found clear evidence that stock-tip spam can influence trading volume and short-term pricing.  Although these effects are rarely sustained over extended periods of time, near term price fluctuations can allow spammers to make money dumping shares within the first minutes or hours of trading.

In 2006, new spamming techniques such as image-spam, often used to deliver stock-tip spam messages, have proven alarmingly effective in penetrating inboxes.  To combat this threat, Tumbleweed recently unveiled new Adaptive Image Filtering (AIF) technology specifically to fight image spam.   According to Tumbleweed’s internal measurements, AIF’s image-spam catch rates exceed 98 percent.

“Many people wonder why there is an epidemic of spam, and how spammers really make money,” said Willy Leichter, director of product marketing at Tumbleweed.  “Now we have clear evidence of how lucrative these schemes can be in the short-term.  Of course, like most scams, these increased values are rarely sustained and often someone is left holding the bag.  We continue to strongly recommend that all organizations deploy up-to-date spam filters and that end-users never respond to unsolicited scam messages.”

The Tumbleweed Message Protection Lab, which has spearheaded this analysis, is a research facility established to analyze spam and study messaging security and protection. The lab analyses email traffic and trends to identify email threats such as spam, image spam, phishing and other types of email threats. The Lab is staffed by experts who continually monitor worldwide spam outbreaks to identify new trends and tactics, and create and publish new heuristics to stop them.

About the Tumbleweed MailGate Product Suite
The Tumbleweed MailGate® Product Suite is a family of products for protecting, filtering and monitoring corporate email, blocking over 99% of inbound spam.  These best-in-breed products enable businesses to manage inbound and outbound traffic, block threats, encrypt messages and optimize network performance.  MailGate products include MailGate Appliance™, MailGate Email Firewall™ software and MailGate Secure Messenger™ software, each optimized for specific environments and security challenges.

• MailGate Appliance: A powerful and easy-to-deploy hardened Linux appliance, providing integrated network edge defense, anti-spam, anti-virus, content filtering, policy management, and outbound encryption.
• MailGate Email Firewall: A comprehensive email security software offering, with functionality ranging from inbound threat prevention to outbound content filtering, monitoring and encryption.
• MailGate Secure Messenger: A policy-based, secure message delivery solution that inspects incoming and outgoing mail and dynamically applies user-defined encryption and routing preferences.

SAFE HARBOR STATEMENT
Tumbleweed cautions that forward-looking statements contained in this press release are based on current plans and expectations as of the date of this press release, and that a number of factors could cause the actual results to differ materially from the guidance given at this time. These factors are described in the Safe Harbor statement below.

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 volatility of stock prices, the efficacy of Tumbleweed’s Message Protection Lab in tracking spam and developing innovative techniques for blocking spam, the impact of stock-tip spam on stock trading volume and stock prices, the ability of spammers to make money from stock-tip spam, and the functionality and performance of Tumbleweed’s adaptive image filtering technology.  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 16, 2006 and Form 10-Q filed November 9, 2006.

Tumbleweed assumes no obligation to update information contained in this press release. Although this release may remain available on Tumbleweed’s website or elsewhere, its continued availability does not indicate that Tumbleweed is reaffirming or confirming any of the information contained herein.

About Tumbleweed
Tumbleweed provides world-class innovative messaging security solutions for organizations of all sizes.  Organizations rely on Tumbleweed's solutions to securely manage their Internet communications, spanning email management to file transfers. Tumbleweed has more than 2,300 customers worldwide, representing industries in Finance, Healthcare, and the U.S. Government. The world’s most security conscious organizations rely upon Tumbleweed technology including Bank of America Securities, JP Morgan Chase & Co., the U.S. Food and Drug Administration, and the U.S. Department of Defense. Our award-winning products build on thirteen years of R&D and 25 security patents in the U.S. alone – many of which are licensed by other security vendors, http://www.tumbleweed.com/company/patents/patent_licenses.html. For more information, visit www.tumbleweed.com.

Tumbleweed, the Arrows logo, MailGate, MailGate Appliance, MailGate Email Firewall, MailGate Secure Messenger, SecureTransport and Validation Authority are either registered trademarks or trademarks of Tumbleweed Communications Corp. in the United States and/or other countries. All other trademarks are the property of their respective owners.

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