Royal Mail has signed a contract with CSC to provide cloud-based IT services to its 30,000 employees.
CSC will provide Royal Mail with access to Microsoft's online services, including online versions of Microsoft Exchange, Sharepoint, Office Communications, and Live Meeting.
"This deal forms part of Royal Mail's drive to invest in new technology to improve efficiency and customer service," said Royal Mail Group head of technology service delivery Carol Olney.
"The Microsoft suite will give people across Royal Mail Group the tools they need to do their jobs more effectively, enabling our business units to collaborate with each other, partners and other external organisations more freely, easily and securely while securing cost savings."
The deal is an extension of a contract between Royal Mail Group and CSC in 2003 to maintain Royal Mail's desktop computers and manage and develop its servers, mainframes and IT services.