It's been just over a month since Yahoo announced its plan to reclaim abandoned usernames, and met with an immediate outcry over privacy concerns. What if you used your Yahoo email as a password reset? Was Yahoo making life easy for identity thieves? Now, the company's finally going public with details of how it plans to protect users from data theft.

The big news is a header system that would signal email providers to check the age of the account before delivering the mail. It's a way to stop email that's meant for the previous owner of the email address. In a post describing the system, Yahoo's Bill Mills described an e-commerce site dropping it into their email reset message: if the Yahoo email has been reset since the e-commerce account was created, then the email won't go through. If enough services sign on, it will mean tying each Yahoo account to the date it was created — and stopping any emails that go through from accounts that are older.

"We don't expect every company and provider out there to adopt this."

It's a strong system, but it needs cooperation from both sides to work, so Yahoo is going to spend the next month reaching out to various networks and mailing lists to try to make their header the industry standard. "We don't expect every company and provider out there to adopt this," said Dylan Casey, senior director of platforms at Yahoo, "but hopefully we can push the industry in this direction." The company has already filed a paper with the Internet Engineer Task Force as a way to give the idea broader credibility. More importantly, Yahoo has enlisted one of the biggest forces in online identity: Facebook. According to the team, Facebook reached out to Yahoo a few days after the initial announcement, offering an email header system as a potential solution. Yahoo liked the idea, and brought on Facebook as an early partner in the process.

Yahoo is also offering simpler protections, like instituting a 30-day period between when an account is deactivated and when another user can claim it. During that time, Yahoo will auto-unsubscribe the account from any mailing lists that send mail to the address. But there are still some issues that haven't been solved, like the policy of deactivating any account that's been inactive for more than a year. Some privacy advocates think that's not long enough, like Credit.com CEO and former director of the New Jersey Division of Consumer Affairs, Adam Levin. "If a scammer somehow manages to get your email information, the risk is that this person will be communicating as if they were you," says Levin. "I think one year is too short. It should be at least two years."

For Yahoo, that's a real risk, but a manageable one. According to Casey, fewer than 7 percent of the deactivated accounts have a mailbox associated with them — meaning they used some Yahoo service, but not Yahoo Mail. In exchange, the company sees a chance to revamp their whole suite of services, enticing users with shiny new handles. "There's been an increased focus in recent quarters on mail and Flickr and the homepage," Casey says, and this username switch is the first step towards bringing back users. "In order to move forward, we have to clean up our past a little."