Security software developer Webroot Software Inc. announced Tuesday that it has merged with Email Systems, an England-based provider of security software-as-a-service. Financial terms of the deal were not disclosed. However, Webroot said both companies will continue to operate within their existing markets. Webroot also said it will retain all of its current employees. As a result of the merger, the company noted, Webroot will shift its focus to providing security software-as-a-service to enterprise organizations, especially small- to medium-sized businesses. Webroot is a private held company headquartered in Boulder, Colo. Its backers include Technology Crossover Ventures, Accel Partners and Mayfield. Based near London, Email Systems is a privately held company and also maintains offices in France, Sweden, Holland and Australia.