Outlook.com encryption [was] unlocked even before official launch, [... top-secret] documents [from the NSA's Special Source Operations (SSO) division] show[s ...]. Microsoft has collaborated closely with US intelligence services to allow users' communications to be intercepted, including helping the National Security Agency to circumvent the company's own encryption:

• The agency already had pre-encryption stage access to email on Outlook.com, including Hotmail: [...] “For Prism collection against Hotmail, Live, and Outlook.com emails will be unaffected because Prism collects this data prior to encryption.”;
• “MS [Microsoft], working with the FBI, developed a surveillance capability” [...] to circumvent its encryption to address concerns that the [NSA] would be unable to intercept web chats [...]. Two months later, [...] Microsoft officially launched the [new] portal.

☞ In a statement, Microsoft said: “When we upgrade or update products we aren't absolved from the need to comply with existing or future lawful demands.”

☞ These communications [can] be collected without an individual warrant if the NSA operative has a 51% belief that: 1) the target is not a US citizen and 2) [it] is not on US soil at the time.

(The NSA's Special Source Operations (SSO) division [is] described by Snowden as the "crown jewel" of the agency. It is responsible for all programs aimed at US communications systems through corporate partnerships such as Prism. [...] Material collected through Prism is routinely shared with the FBI and CIA, with one NSA document describing the program as a "team sport".)