Mr. President, You've Got Mail, the Vetted Kind

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The White House, Washington, D.C.

The latest ricin-laced letter addressed to President Obama was intercepted this week at a state-of-the-art Secret Service screening facility in Washington that since 2010 has served as the first line of defense in keeping dangerous missives away from the White House.

But the Secret Service has been involved in tracking suspicious packages headed for the White House since 1940, a spokesman for the organization said.

Mail used to be delivered directly to 1600 Pennsylvania Ave., much to the delight of past presidents like Ronald Reagan. According to Nancy Theis, who worked in Reagan's correspondence department, he would sometimes drop by the White House mailroom himself.

All that changed in 1996, when a remote delivery site for White House mail was opened in the Anacostia neighborhood in Washington.

Security was beefed up even further in 2001 when, after the anthrax scare, the Secret Service began screening all mail items destined for the White House. That year, the screening facility was moved to Maryland to and housed there for the rest of the decade.

But concerns over bioterrorism and other mail-borne threats mounted as "mail incidents" increased. In 2004, there were 234 such issues involving items destined for the White House, 24 of which contained threat letters, according to the Department of Homeland Security's fiscal year 2006 budget request.

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So in 2006 Congress approved funding for the Secret Service's current state-of-the-art facility, which was completed in 2010. Officials declined to reveal its exact location. It costs about $18.4 million in 2012 to run the screening operation, which tracks about 1 million pieces of mail each year.

The off-site screening is only the first hurdle a letter must overcome before it has a chance to land on the president's desk. After it's deemed safe, White House mail heads to a sorting facility in the Eisenhower Executive Office Building, right next to, but completely separate from, the White House.

So the next time you want to get in touch with the commander-in-chief and are looking for a speedy response, consider this mail-sorting process. And then perhaps consider sending a email instead.

_By NBC News' Ali Weinberg.