curl --location --request POST 'https://prod.your-api-server.com/campaign-preview/send' \
--header 'Authorization: <api-key>' \
--header 'Content-Type: application/json' \
--data-raw '{
"campaignId": "550e8400-e29b-41d4-a716-446655440000"
}'{
"success": true,
"message": "string",
"emailsSent": 0
}