Yahoo! said to have used a spam filter to comply with an email surveillance secret court order

Yahoo! is said to have used a system intended to scan emails for child pornography and spam in order to respond to a secret court order issued in the US and requiring the company to search for messages containing a computer signature tied to the communications of a state-sponsored terrorist organisation. Yahoo!, which was barred from disclosing the matter, customised an existing scanning system for all incoming email traffic, allowing it to store and made available to the FBI a copy of any message it found that contained the specific digital signature. The order is seen as unusual, because it lead to the scanning of all Yahoo! users’ emails rather than individual accounts. The system, however, is said to be no longer in use.