@v.akra from SuiteAnswers: “NetSuite does not support the use of IP addresses to access or manage access to any NetSuite services. Using IP addresses to manage access is sometimes called whitelisting. If you use IP addresses to access or manage access to NetSuite — in firewall or proxy configuration, for accessing SuiteTalk (web services) or any other services — it is your responsibility to update these settings when NetSuite IP address ranges change. Technical Support will not provide a list of IP addresses. The IP addresses of NetSuite services may change at any time and without notice. In certain cases, for example, email service, you should rely on methods that do not require explicit reference to any NetSuite IP address. For more information, see Sender Policy Framework (SPF) in Email Best Practices.”