Note: This article applies only to Office 365 operated by 21Vianet in China.
By default, the SharePoint Newsfeed is your organization’s Enterprise Social Collaboration network. Everyone with a SharePoint Online subscription will see Newsfeed in the Office 365 global navigation.
Yammer.com is an alternative to the SharePoint Newsfeed, but is not available for your Office 365 service. Switching the Enterprise Social Collaboration setting in the SharePoint admin center currently does not work for your organization.
To learn more about using and posting in Newsfeed, see Post something to everyone.