1. A non-transitory machine readable medium storing instructions which when executed by one or more data processing systems cause the one or more data processing systems to perform a method comprising: receiving and storing account information from a plurality of organizations including a first organization, the account information used to create one or more messaging accounts for each organization to conduct one or more messaging sessions with customers or users of each organization through a messaging system that provides a messaging service to a plurality of user devices that each include a messaging application that is configured to send and receive messages through the messaging system, wherein a first account information for the first organization includes data specifying one or more limitations on the amount of online messaging sessions that can be initiated or maintained or established with the first organization; receiving a request, from a first user device, to initiate a messaging session with the first organization; determining whether an amount of online messaging sessions between the first organization and a plurality of customers or users of the first organization exceeds the one or more limitations for the first organization; initiating the messaging session between the first user device and the first organization when the determined amount does not exceed the one or more limitations.