As for international mail coming into the United States, the government already has the right to open those letters without a warrant. Under a trade act passed in 2002, 107 H.R. 3009, Congress expanded the Custom Service's ability to open international mail without a warrant.
When it comes to electronic mail, the government may not need a warrant to search your messages. By claiming that your e-mail is stored on third-party servers held by Yahoo and such companies and citing the Stored Communications Act, the government doesn't need to get access to your personal computer at home in order to read your e-mail.
In a recent mail-fraud case, the Federal Trade Commission and FBI simply obtained a court order -- not a warrant -- to access the e-mail accounts of Steven Warshak, a businessman who sells male enhancement products online.
ABC News' Marcus Baram, Michael S. James, David Kerley and Ann Compton contributed to this report.