Shopify can link orders only to a contact that comes from Shopify itself. So if you have contacts that have been added to your PlentyONE backend via another method – for example, via the shop or by manual entry – an order from Shopify cannot be assigned to that contact.

When a customer places an order with you via Shopify for the first time, a contact is created, and all subsequent orders from that customer are then assigned to that contact. 

For customers who do not have an account in the Shopify shop, the following applies: If their email address changes, a new contact is created.

So it’s impossible to avoid having duplicate contacts, as Shopify insists on having its own.

When a contact is imported from Shopify or enters the system via an order, an External Contact ID and a Shopify Referrer ID are stored for that contact.

• The External Contact ID is visible in the UI next to the contact. The field is labelled External number.
• The Shopify Referrer ID is not visible in the UI for the contact and is only stored in the database.

For this reason, a contact originating from a source other than Shopify cannot be converted into a Shopify contact.

In accordance with the General Data Protection Regulation (GDPR), contacts are always created as Guest in Shopify.

You can convert Guest contacts into regular contacts.