1. A method executed on a computing device for integrating functionality of a plurality of customer relationship management (CRM) applications/instances into an email, contact management, scheduling (ECS) application user interface, the method comprising: loading a CRM integration module in an instance of the ECS application; selecting one of the plurality of CRM applications/instances based on at least one from a set of: automatic selection and user selection; determining a context for the selected CRM application/instance; presenting a sub-user interface associated with CRM functionality related to the selected CRM application/instance within a user interface of the ECS application; and managing states of the selected CRM application/instance and remaining CRM applications/instances through a state manager.