With the cloud, the City is streamlining and consolidating these three systems into one, reducing outages, improving security and ensuring that all employees who need access to email and desktop applications have them.

ENGADGET: Microsoft to provide cloud services for city of Chicago in four year deal

Previously, the City managed three separate email systems internally, providing challenges to efficiency and security.

ENGADGET: Microsoft to provide cloud services for city of Chicago in four year deal

Washington (CNN) -- The companies that control critical infrastructure in the United States are reporting higher numbers of attacks on their systems over the past three years, according to a report issued by the Department of Homeland Security.

CNN: Homeland Security cites sharp rise in cyber attacks