curl --request POST \
  --url https://{your-workspace}.neetopublish.com/api/v1/email_subscriptions \
  --header 'Content-Type: application/json' \
  --header 'X-Api-Key: <x-api-key>' \
  --data '{
  "subscription": {
    "email": "jsmith@example.com"
  }
}'

{
  "message": "<string>"
}