The Obama administration for over two years allowed the National Security Agency to collect enormous amounts of metadata on e-mail usage by Americans, according to one of the latest leaks of government documents by the now-famous whistle-blower Edward J. Snowden.

But what is e-mail metadata anyway? It’s information about the people you’re sending e-mails to and receiving e-mails from, and the times that the messages were sent — as opposed to the contents of the messages. It’s the digital equivalent of a postal service worker looking at your mail envelope instead of opening it up and reading what’s inside.

That sounds harmless, but it turns out your e-mail metadata can be used to connect the dots of your life story. I learned this from participating in Immersion, a project by M.I.T.’s Media Laboratory, earlier reported by my colleague Juliet Lapidos. Immersion is a tool that mines your e-mail metadata and automatically stitches it all together into an interactive graphic. The result is a creepy spider web showing all the people you’ve corresponded with, how they know each other, and who your closest friends and professional partners are.

After entering my Google mail credentials, Immersion took five minutes to stitch together metadata from e-mails going back eight years. A quick glimpse at my results gives an accurate description of my life.

In an Immersion chart, each person is represented by dots. The more you’ve e-mailed with the person, the bigger the dot gets. In my results, the biggest dot was my boss at my last job; the second biggest was my long-term former girlfriend. The medium-size ones were some of my closest friends. Lines that connected some dots showed friends of mine who knew each other.

One can imagine that mining the metadata of a person suspected of a crime is an effective tool to track down his accomplices. But considering how easily and quickly this can be done, it’s not hard to assume that the government collects these records on just about everyone. That seems to be the point that Immersion is trying to make.

After being thoroughly disturbed, I removed Immersion’s permission to access my account and asked the project to delete my metadata. But it left me with the feeling that more about me is already known than I’d like, and it’s already too late.