Yahoo last week published the text of three National Security Letters it received from the FBI in 2013. The letters demand the names, addresses, length of service, and electronic communications transactional records -- existing transaction and activity logs and all email header information -- of the targets. However, they do not ask for any content -- either the subject lines or bodies of emails. Yahoo sent the FBI the name, address and length of service for each of the accounts identified in two of the NSLs.