As if on cue ...

A technical glitch gave the FBI access to the e-mail messages from an entire computer network — perhaps hundreds of accounts or more — instead of simply the lone e-mail address that was approved by a secret intelligence court as part of a national security investigation, according to an internal report of the 2006 episode.

FBI officials blamed an “apparent miscommunication” with the unnamed Internet provider, which mistakenly turned over all the e-mail from a small e-mail domain for which it served as host. The records were ultimately destroyed, officials said.

Bureau officials noticed a “surge” in the e-mail activity they were monitoring and realized that the provider had mistakenly set its filtering equipment to trap far more data than a judge had actually authorized.

The episode is an unusual example of what has become a regular if little-noticed occurrence, as American officials have expanded their technological tools: government officials, or the private companies they rely on for surveillance operations, sometimes foul up their instructions about what they can and cannot collect.