How do we get the next task Id of a User Input Task. This has to be entered in t

You can send the email after the task is instantiated (e.g. a paralel flow one that goes to the task to instantiate it, one that goes to a timer to wait for the task to be instantiated).

The flow that has the timer would then go to a script task that can call a custom function you will have to create (forum.appian.com/.../ProcessExecutionService.html, int, int, int, java.lang.Integer, java.lang.Integer) to get the current tasks for process and based on your business logic get the desired task from that process then pass that information to the Send Email node.

You can send the email after the task is instantiated (e.g. a paralel flow one that goes to the task to instantiate it, one that goes to a timer to wait for the task to be instantiated).

The flow that has the timer would then go to a script task that can call a custom function you will have to create (forum.appian.com/.../ProcessExecutionService.html, int, int, int, java.lang.Integer, java.lang.Integer) to get the current tasks for process and based on your business logic get the desired task from that process then pass that information to the Send Email node.