How can customers be notified of specific items coming into inventory?

[SeanPatrickH]

I would like a feature for my customers to be able to put in a specific query of an item that they would like to have that we don't carry and if it later comes into inventory, them to be notified by email. I cannot find such an app. Or, I can't figure out how to do it with Shopify. Please direct me if you know of anything.  Thanks.

I call it "Items that I am looking for" for the customer.

[SomeUsernameHe]

I think your best bet for this situation is to use a custom form, possibly connected to klaviyo or Mailchimp where you can segment them somehow.

Or, the marketing side of me would tell you to have a signup form for your mailing list with text input to add new products they are looking for. Then maybe sign them up for product release emails only. This wouldn't be a complete solution as this would send them all "new product release" emails, but it would be a good start. 

I didn't see any apps right away that are able to assist with this, and this would be something a database would be highly recommended for to keep customer requests.