According to an article on Yahoo at https://goo.gl/HkPgCK:
In a letter today to James Clapper, Director of National Intelligence (DNI), Yahoo is formally urging that the U.S. government provide its citizens with clarification around national security orders they issue to internet companies to obtain user data.
While the letter makes specific reference to recent allegations against Yahoo, it is intended to set a stronger precedent of transparency for our users and all citizens who could be affected by government requests for user data. As we’ve said before, recent press reports have been misleading; the mail scanning described in the article does not exist on our systems.
DNI’s mission statement refers to “responsible and secure information sharing.” We therefore trust that the U.S. government recognizes the importance of clarifying the record in this case. On behalf of Yahoo and our global community of users, we request that the Office of the Director of National Intelligence expeditiously clarify this matter.