An extensibility model is used to provide active and interactive functionality in communication items, but the embodiments are not so limited. A computer system of an embodiment includes components configured to identify one or more activation triggers that operate to activate gadget code using an isolated code execution environment as part of injecting content into an email communication. A method of one embodiment provides an extensibility framework for using defined gadget triggers and associated gadget functionality as part of automatically injecting content inline with a mail message.