I believe you have to use custom actions to do that. A while back I did something similar. But to trigger the action, the bot needs to identify that it belongs to a particular intent only then it will work.
Define a slot as unfeaturized. Then whenever that intent is identified, go to your custom actions do something like this:
class Actionform_2(Action):
def name(self):
return "form_2"
def run(self, dispatcher, tracker, domain):
message = tracker.latest_message.get('text')
dispatcher.utter_message(message)
return [SlotSet('email', message)] #slot value can only be set by returning it