Charlie Savage and Nicole Perlroth:

A system intended to scan emails for child pornography and spam helped Yahoo satisfy a secret court order requiring it to search for messages containing a computer “signature” tied to the communications of a state-sponsored terrorist organization, several people familiar with the matter said on Wednesday.

Two government officials who spoke on the condition of anonymity said the Justice Department obtained an individualized order from a judge of the Foreign Intelligence Surveillance Court last year. Yahoo was barred from disclosing the matter.

To comply, Yahoo customized an existing scanning system for all incoming email traffic, which also looks for malware, according to one of the officials and to a third person familiar with Yahoo’s response, who also spoke on the condition of anonymity.

With some modifications, the system stored and made available to the Federal Bureau of Investigation a copy of any messages it found that contained the digital signature. The collection is no longer taking place, those two people said.

So Yahoo seems to be the first to willingly give in to the government. I’d delete my email account there immediately, if I had one.