In April 2004, Google launched Gmail, an invitation-only version of its e-mail service. At the time, Gmail offered 1 gigabyte of storage space, an amount that seemed impossibly generous compared to the 2, 4 or 10 megabytes offered by many other popular e-mail providers. While Gmail was not the first e-mail provider to grant its users so much storage space, it was the most prominent. With its characteristic panache and intuitive interface, Gmail took off and eventually opened to all users around the world.

Photo courtesy Dreamstime It turns out that the U.S. government has been using the Stored Communications Act (SCA) to read private e-mails without a search warrant.

Google's competitors followed suit, as e-mail service providers began engaging in a mini-electronic arms race of ever-increasing storage capacity. Yahoo attempted to trump them all when it announced in March 2007 that it would soon offer unlimited storage space for users of its Yahoo! Mail service. As of today, the other two of the "big three" e-mail providers -- Microsoft's Windows Live Hotmail (formerly MSN Hotmail) and Google's Gmail -- offer, respectively, 2 gigabytes and 2.866 gigabytes of storage space.

The great leaps in e-mail storage capacity were a boon to Internet users. Now people can send larger attachments and many might never have to delete an e-mail again. Never again will you dig around for a now-essential message only to realize that you deleted it a week ago because it seemed unimportant. Sounds great, right?

Video Gallery: Online Security and Privacy Issues Rich Mogull is a research vice president specializing in security and privacy at Gartner, the best known analyst group in the IT and security industries. Check out our video on security and privacy online. Our near-constant Web connections creates even more opportunities for cyber crime. Watch this video for ways to keep your keeping your information secure.

Not quite. It turns out that the U.S. government has been using the Stored Communications Act (SCA) to read private e-mails without a search warrant. These are e-mails stored on services like Gmail, Yahoo and Hotmail. If the government wants to read e-mails that on their way to a recipient, they need to have a special type of search warrant, a wiretap order. Wiretap warrants can be difficult to get. So instead of worrying about in-transit e-mails, the government secretly accessed stored e-mails, justifying its conduct under the SCA. Increasingly large amounts of storage space mean that many people never delete e-mails (this writer does so only rarely). So a person's entire history of electronic communication could be available to the government without a judge first signing off on a warrant. ­

­The issue worried civil liberties and Internet rights advocates, and a recent court ruling was in their favor. On Monday, June 18, a panel of three judges from the U.S. 6th Circuit Court of Appeals declared the government's actions and the SCA unconstitutional. The result is that stored e-mails are now more secure from government eavesdropping, since the government now has to get a warrant to read the stored e-mails of someone they're investigating.

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We'll examine the ruling and exactly what it means in the next section.