The new offering will enable customers to buy Office 365 for Business and Enterprise directly from San Antonio-based Rackspace with migration assistance and tier-one support. "Massive-scale platforms for infrastructure-as-a-service and software-as-a-service are carving out a permanent piece of the competitive landscape and Microsoft's Office 365 is one of those gaining steady traction," said Philbert Shih , managing director of structure research at Rackspace.