North Island Credit Union in Chula Vista, Calif., has agreed to use Iconix Inc.'s Truemark security system for outgoing e-mail.

Truemark places a padlock icon and the sender's logo next to e-mails sent by Iconix clients. The system, which works with Webmail providers such as Yahoo Inc., Google Inc., Microsoft Corp., and AOL LLC, is meant to help users distinguish valid e-mails from those sent by phishers, which would not be able to use the sender's logo and the padlock icon. Iconix, of Santa Clara, Calif., said North Island has been using Truemark since Oct. 5.

David Delacalzada, the credit union's chief information officer, said in an Iconix press release that during a Federal Bureau of Investigation probe into an identity theft ring, North Island "temporarily stopped all e-mail solicitation communication" to curb losses.

He said the Truemark system "gives users the confidence of knowing they are actually receiving e-mail from the credit union, not a phishing trickster."

Truemark is already in use by eBay Inc.'s PayPal online payments unit, which signed on this year. Iconix says it also can use publicly available information to authenticate e-mails sent by financial institutions with which it does not have a direct business relationship.

Jeff Wilbur, Iconix's vice president of marketing, said its service "makes it easy for users to recognize legitimate messages from companies they care about, and avoid being tricked by fraudulent messages in their inbox."