The NSA collects half a million buddy lists and inboxes a day. Is one of them yours?

At the Washington Post, Barton Gellman and Ashkan Soltani report on a new finding in the top secret documents provided by former National Security Agency contractor Edward Snowden: The NSA is gathering "hundreds of millions of contact lists" from personal e-mail and IM accounts. Many of these accounts belong to Americans. Maybe one of them belongs to you.
The collection program had not previously been publicly revealed. According to the Washington Post story, here's how it works: the NSA intercepts e-mail address books and “buddy lists” from IM services as that data transits through the global network, for instance at session log-on and log-off. And all of this is made possible with help from compliant carriers.

Rather than targeting individual users, the NSA is gathering contact lists in large numbers that amount to a sizable fraction of the world’s e-mail and instant messaging accounts. Analysis of that data enables the agency to search for hidden connections and map relationships within a much smaller universe of foreign intelligence targets. During a single day last year, the NSA’s Special Source Operations branch collected 444,743 e-mail address books from Yahoo, 105,068 from Hotmail, 82,857 from Facebook, 33,697 from Gmail and 22,881 from unspecified other providers, according to an internal NSA PowerPoint presentation. Those figures, described as a typical daily intake in the document, correspond to a rate of more than 250 million per year.
Each day, the presentation said, the NSA collects contacts from an estimated 500,000 buddy lists on live-chat services as well as from the “in-box” displays of Web-based e-mail accounts.

Frame from leaked NSA presentation, published by the Washington Post.

"NSA collects millions of e-mail address books globally"

Read the documents here.