In simple words this means that your your email is encrypted both ways and thus better protected as it travels between Microsoft and other email providers. However the disadvantage of TLS usage is that it also requires the other side the recipient email service provider to have the TLS too for proper privacy execution. To this end, Microsoft has been working with other service providers to improve and test the encryption including Deutsche Telekom, Yandex and Mail.Ru, the company said in a blog post.
In addition to the availability of TLS, Outlook.com has also enabled Perfect Forward Secrecy (PFS) encryption support for sending and receiving mail between email providers. Forward secrecy uses a different encryption key for every connection, making it more difficult for attackers to decrypt connections.
The Company has also enabled PFS encryption support for its OneDrive Customers.
OneDrive customers now automatically get forward secrecy when accessing OneDrive through onedrive.live.com, our mobile OneDrive application and our sync clients. As with Outlook.com’s email transfer, this makes it more difficult for attackers to decrypt connections between their systems and OneDrive.
Microsoft also announced the opening of the first Microsoft Transparency Center which provide participating governments with the ability to review source code for Microsoft’s key products, assure themselves of their software integrity, and confirm that there are no “back doors.”open in its software.