Stockbroker Van der Moolen Uses Tumbleweed to Secure eMail

REDWOOD CITY, CA - May 21, 2001 - Tumbleweed® Communications Corp. (Nasdaq:TMWD), a leading provider of mission critical messaging software, today announced that all systems trader Van der Moolen (Euronext: MOO) uses Tumbleweed's messaging solutions to organise and secure all its email.

"Van der Moolen uses our MMS Mail software. The MMS mail software offers Van der Moolen the possibility to regulate email traffic within their organisation," said Arien Klomp, Country Manager Benelux of Tumbleweed. "All incoming and outgoing email is checked on viruses and email restrictions can be implemented. Furthermore, a disclaimer can be automatically attached to every email. email protocol policies can be centrally defined. There is no need to install new desktop software and employees do not need special training as all the software runs on server level."

"We were looking for a supplier with flexible solutions and a good track record. Tumbleweed has proven itself and offers us the means to secure and organize the email traffic of all our employees across eight locations in Europe and the United States. It is very important for us to ensure that our email traffic is checked thoroughly," said René Hebels, IT Manager at Van der Moolen.

Besides protection against viruses and network bandwidth management, Tumbleweed's Messaging Management System™ (MMS™) also offers Van der Moolen other advantages. MMS enables the stockbroker to define filters to control their own online communications. In addition, new communication services can be rapidly implemented to protect and distribute information over the Internet. The MMS-server enables an organisation to protect the email traffic between all connected computers without having to install new desktop software and being confronted with new procedures.

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.

About Van der Moolen
Van der Moolen is a transatlantic trading house active in equities and equity-related instruments. We are active as specialist and as a market maker in security markets in Europe and the United States. On the AEX Exchanges in Amsterdam, we are the market leader. On the New York Stock Exchange, we are among the Top 5 specialists, with a 10% share of transaction volumes. In addition, we operate on most of the main European exchanges as a market maker in European shares and equity options, and as a specialist/market maker in equity options on the important options exchanges of the United States. Van der Moolen Holding NV's own shares have been listed on the stock exchange of Amsterdam Exchanges (AEX) since 1986. Option series on Van der Moolen shares are listed on the AEX Options Exchange, where they are a component of the AMX (AEX Midkap Index).

Van der Moolen employs 400 people in seven locations worldwide. In 1999, gross revenues amounted to EUR 240.3 million and net income came to EUR 105.4 million. More information on: www.vandermoolen.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.