From Spiffy Stores Knowledge Base
Product Reviews are currently in Beta testing. They do require theme support, and we are in the process of updating themes.
If you are using the latest version of the Melbourne, Sydney, Bendigo, Simple or Vintage themes, then they should be available to you, and we would love to hear your feedback. Please email email@example.com with any feedback.
You can enable product reviews in the Products section of your store's admin.
You can enable the mail after purchase function in the Preferences -> General Settings section of your store's admin.
You can add a logo or edit the automated mail after purchase email in the Design & Assets -> Email Templates section of your store's admin.