A message below appeared in our Office 365 Tenant Message Centre,

New Feature: Mobile Push Notifications for OneDrive for Business and SharePoint
MC77757
Published On : Sep 19, 2016
Expires On : Jan 19, 2017
Mobile Push Notifications for OneDrive for Business and SharePoint is a new Office 365 feature. We are currently rolling this out to all customers and we expect to have this rollout completed by December 31, 2016.

How does this affect me?

This new feature will allow end users to receive mobile push notifications when other people share files and folders with them from OneDrive for Business and SharePoint Online. Because there will be some data, including the user and file name, passed through Google Cloud Messaging and Apple Push Notification Service, we have also enabled an admin toggle to disable any mobile notifications about content changes in your tenant.

What do I need to do to prepare for this change?

This has administrative controls to enable and disable. This feature is on by default and can be found in the SharePoint Admin Center under “Site Settings”.