Very useful post. I personally so believe in not sending survey links through mass mailing platform. If you're really keen on feedback, write personal email to a selected group of people and you would definitely get some actionable feedback by few of them.
Bucket your user search from whom you would like to have feedback into a couple of categories:
Super active users:
They use the crap out of your product, consistently. I’d be curious to speak with them to understand what they like about your product and why it’s so valuable to them.
Drive by users:
People who check out your application quickly and then leave, never to return. What was their impression? Why didn’t they stick around? If you’re using a product like Fullstory, are you able to see what they did in your product?
Engaged people who quit
I’d look for people who used it for a minimum of some period (a month? Multiple weeks?) and then stopped using it. These people presumably understand at least a portion of your product, but then took action to stop using it.
Read the full post at - https://medium.com/startup-grind/identify-users-with-the-most-valuable-feedback-4c984987265e#.s6vfbi7nq