This is an important announcement

I already announced in April that Microsoft was introducing a new way to provide Office 365 endpoints details (IP addresses ranges for each services) using web services (see http://blog.hametbenoit.info/2018/04/04/office-365-new-and-better-way-to-manage-office-365-services-ip-addresses-updates)

Well, it has now be announced that the existing RSS and XML services providing the same information are going to be retired by October 2018 so you need to quickly start looking at the new web service option to get and maintain your whitelist for Office 365 services (see https://support.office.com/en-us/article/managing-office-365-endpoints-99cab9d4-ef59-4207-9f2b-3728eb46bf9a – section Web service)