Tumbleweed Communications Corp., a provider of secure messaging applications for businesses and government organizations using the Internet, announced that it has been granted U.S. Patent No. 6,487,599 by U.S. Patent and Trademark Office. Tumbleweed is suing PayPal, Yahoo and other companies for patent infringement, and said the new patent will strengthen its position in litigation.

The new patent, titled "Electronic Document Delivery System In Which Notification Of Said Electronic Document Is Sent To A Recipient Thereof," is a continuation of U.S. Patent No. 6,192,407 titled "Private, Trackable URLs For Directed Document Delivery."

"Essentially, the U.S. Patent and Trademark Office affirmed today that Tumbleweed's patents cover the use of personalized, trackable URLs to deliver "data" and "electronic information" as well as "documents" - a term used in the earlier patent claims," said Bernard J. Cassidy, Tumbleweed's Vice President and General Counsel.