There is so much implicit data available in e-mail answers if you just are able to ask the right question. It’s the same thing as running polls. You want to capture insights or data to know more about your audience. The best polls, to me, are context based, two ways: towards the clients, towards you as an insight. The key is in asking the right questions, combined.
Allow me to demonstrate with an example and how easy it is to experiment with new ideas to sell or segment (yes, you could even segment with this approach).