curl --request POST \
  --url https://api.embedreach.com/partner/channel/integrations \
  --header 'Content-Type: application/json' \
  --data '
{
  "channel_provider": "reach-managed",
  "channel_integration_type": "email",
  "channel_integration_metadata": {
    "type": "reach-managed",
    "customDomainEnabled": true
  }
}
'

{
  "success": true,
  "message": "<string>",
  "data": {
    "id": "<string>",
    "channel_integration_metadata": {
      "type": "reach-managed"
    }
  }
}