Mailblocks, which was started by WebTV co-founder Phil Goldman, sells technology that helps Web surfers ward off spam by challenging messages from unknown or automated senders, a system known as "challenge/reponse." Its lawsuit is a lightning-speed response toa similar "permission based" spam-blocking technology that subscribers will be able to use later this month.
Mailblocks alleges that EarthLink initiated discussions related to its service, but nothing came of the talks. However, EarthLink's newly proposed service "as advertised" will infringe on its patent, the company says.
"Mailblocks developed and owns the patents for challenge/response, and we intend to vigorously enforce our rights to the fullest extent permitted by law," Mailblocks chief Phil Goldman said in a statement.
EarthLink could not immediately be reached for comment.
Mailblocks' patented technology requires senders, who are not listed on the user's accepted recipient list, to reply to a question before their message and future messages will be sent. As a result, the system helps thwart machine-generated spam, which cannot reply to the e-mail. The service launched in late March.
EarthLink said its coming service, called SpamBlocker, will automatically generate an e-mail in response to all incoming mail. The original sender must then respond to a question in that e-mail before the message is delivered to its intended recipient. Once authorized, that person's e-mail is placed on a permitted list.
The company also uses Brightmail's antispam filtering tool called "the spaminator" to filter out much of that spam before it reaches its subscribers' in-boxes. But as the spammers tweak their messages, a greater number of e-mails are able to bypass filters.
At the same time, EarthLink is focusing on legal measures of a different kind. The company on Wednesday won a $16.4 million judgment in a New York court against a Buffalo, N.Y., spammer. The junk e-mailer had sent nearly a billion unsolicited commercial e-mails since early last year.
Mailblocks' suit was filed in the United States District Court for the Central District of California.