Hi Tatiana!
Liam here from Shopify - thank you for your question :)
There are number of apps which should be able to generate customisable emails which could be sent to POS customers requesting a review of a product. The following are three great apps for increasing the amount of feedback you get by automating the review invitation process.
It is also possible to create notifications based on certain products and situations using these apps.
Hope this helps, if you have any other questions, just let me know!
Cheers,
Liam
Shopify Guru
support@shopify.com