A Schneier blog post
notes that three would-be bombers were recently convicted in the UK thanks in large part to e-mail communication that was intercepted by the US National Security Agency
. This was the second time the men had faced criminal charges; in the first trial, the prosecution was unable to make part of their case because they didn't yet have the e-mail evidence. "Although British prosecutors were eager to use the e-mails in their second trial against the three plotters, British courts prohibit the use of evidence obtained through interception. So last January, a US court issued warrants directly to Yahoo to hand over the same correspondence." The BBC posted a number of e-mails used as evidence in the trial
. The communication is coded, and some of it looks like what you might find in your spam folder, but the article also provides the prosecution's explanation of what they mean.