If you are filtering your web traffic using IP address filtering you will need to update the IP’s you use to filter. Please check the link below to determine what changes are required.
Note that for customers with firewall filters, Office 365 recommends using URL filtering vs. IP address filtering. URL filtering does not require any action related to this update.
For additional updates on IP changes, please subscribe to the RSS feed indicated here: http://go.microsoft.com/fwlink/p/?linkid=236301