The decision, filed Monday in the U.S. district court in Seattle, could be a setback to Mailblocks in enforcing rights to two patents for challenge-response technology, or techniques for differentiating between e-mail sent by humans and that sent by automated junk-mailers.
The court ruled in favor of Spam Arrest's motion to stay the request despite its admission of patent infringement. Spam Arrest argued instead that Mailblocks' patents were invalid because of "prior art"--that is, because systems for challenge-response technology predate Mailblocks' own. The company also requested that similar pending patent complaints by Mailblocks, such as one against EarthLink, should be combined and heard as one by the Multidistrict Litigation Panel, which specializes in hearing multiple complaints.
"The preliminary injunction must be denied because there are substantial questions as to Mailblocks' chances of success on the merits (and) because Mailblocks has not demonstrated that it will suffer irreparable injury if the injunction is denied," according to the filing.
In March, Mailblocks launched its antispam software, which centers on challenge-response technology and for which it purchased two patents: 6,199,102 (filed in 1997) and 6,112,227 (filed in 1998). Intended to block spam, the technology requires senders who are not listed on a person's accepted-recipient list to reply to a question before their message will be sent. As a result, the system helps thwart machine-generated spam, which cannot reply to the e-mail.
Because spam has turned into an IT nightmare, more and more e-mail providers and software makers are embracing such systems as a junk-mail defense. For example, Yahoo recently introduced a similar system to help customers of its Web-based mail service with spam.
But Mailblocks has aggressively sought to protect its patent rights by filing complaints against EarthLink, MailFrontier and others. Phil Goldman, CEO of Mailblocks, said that a preliminary injunction had been a long shot for the patent case and that the decision should not affect a favorable ruling in the end.
"We are even more confident that at trial the court will find that Spam Arrest violates our patents and that prior art does not exist for this," he said.
Goldman said that the company filed suit against Spam Arrest because it openly admits that it infringes on Mailblocks' patent, yet would not discuss a partnership. The company has already dropped a similar suit against MailFrontier because it entered into discussions, he said. Also, the company expects to announce its first licensing partner later this week.
Spam Arrest could not be immediately reached for comment.