For Apps try and be proactive about feedback and include a couple of (visible) options:

1. I don't like this app (opens email feedback to you)

2. I like this app (opens feedback to the store)

Typical example for a phone App:

http://www.windowsphone.com/s?appid=798a731f-c0f0-4c2a-b8b1-c1590a0d66ac