We run a consignment shop. I want to send an email notification to a consignor when their item is sold (via a transaction made on a Square Terminal). I was figuring on adding a custom text field to each inventory item with the email address of the consignor. (Although other suggestions are welcome.) Questions: 1) is this possible? 2) Could you point me in the right direction to get started?
At this time there isn’t a way from the Square Terminal to trigger an email to a consigner of an item that sells. However if your building a custom application that’s managing consigners you can listen to inventory.count.updated webhooks. When you get a updated event for a catalog object that was sold you can match it with the consignor in your data base to trigger an email notification. 
Hello Maxim Time Clock@Nikko963,
Yes, it is possible to send an email notification to a consignor when an item is slod through a Square Terminal. You an use Square’s Webhooks to trigger an email notification after a sale.