1. A non-transitory machine-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, cause the one or more processors to carry out the steps of: receiving a communication destined to a first tenant of a plurality of tenants using at least one on-demand service; applying a plurality of security processes to the communication to obtain a return code, the return code being associated with at least one of the plurality of security processes; and determining, based at least in part on the return code, whether to process the communication.