The possible reason that this might be going to spam is because your emails are coming from Working Feedback's mail servers rather than your own. You will reap rewards with better opening rates as your email address is already known and trusted by your customers.

1. Head over to your Dashboard
2. Click on 'Collect' from the top menu
3. Select 'Send a one-off feedback request'
4. Pick the advanced tab from options, and follow instructions