Microsoft has worked closely with US intelligence agencies to intercept users' communications, going as far as helping the NSA break the company's own encryptions, new secret files handed to the Guardian by Edward Snowden have revealed.
Before the launch of the new Outlook.com portal, Microsoft helped the NSA circumvent encryption used by the service, after the agency expressed concerns that it would not be able to read messages sent through the new system.
The documents show that the NSA had long held pre-encryption stage access to emails sent through Hotmail. Microsoft also worked with the FBI to explain an Outlook.com feature which enabled users to create email aliases.
In a statement to the Guardian, Microsoft said, "When we upgrade or update products we aren't absolved from the need to comply with existing or future lawful demands."
The company also worked to allow the NSA easier access to its cloud storage service SkyDrive via the Prism data collection programme. Microsoft previously denied all knowledge of Prism and said they had never given the government direct access to its servers.
This was something reiterated by Microsoft in this week's statement. "We only ever comply with orders about specific accounts or identifiers, and we would not respond to the kind of blanket orders discussed in the press over the past few weeks," it read.
Microsoft's most recent marketing campaign was launched in April with the slogan "Your privacy is our priority".
To obtain a secret court order for blanket collection of communications without an individual warrant, an NSA operative needs to be just 51 per cent sure the target is not a US citizen or in the country at the time.
Shawn Turner, spokesman for the director of US National Intelligence, and Judith Emmel, spokeswoman for the NSA, said in a joint statement, "The articles describe court-ordered surveillance – and a US company's efforts to comply with these legally mandated requirements.
"The US operates its programs under a strict oversight regime, with careful monitoring by the courts, Congress and the Director of National Intelligence. Not all countries have equivalent oversight requirements to protect civil liberties and privacy."