These dynamic handlers can be enabled by using dynamically loaded modules. The ability to handle dynamic content internally means it's easier to configure dynamic handling as usual. The Job Function Email List link does not require additional software and the module can be easily replaced if content needs change. Initially there was no ability to handle dynamic content.
In order to process and other queries with dynamic content one must switch to an external processor to execute and wait for the displayed content to be sent back. The results can then be forwarded to the client. For administrators this means that communication between and must be configured via one of the protocols. This can complicate things a bit, especially when trying to predict the number.