> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sellauth.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Create Customer

> Creates a customer by email, or returns the existing customer with that email. The newsletter fields only apply to a newly created customer; when "created" is false, use the Set Customer Newsletter endpoint to change it.



## API Specification

The full API specification for this endpoint is available in the [documentation index](https://docs.sellauth.com/llms.txt).


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