Exchange Online is part of the Office 365 suite of products.
End users - see Office help and training
Assign admin permissions
Learn about the Exchange Admin Center
To manage Exchange Online
As an administrator for your Office 365 tenant, you manage your organization's Exchange Online service in the Exchange admin center. Here's how you get there:
Sign in to Office 365 using your work or school account, and then choose the Admin tile.
In the Office 365 admin center, choose Admin centers / Exchange.
For an introduction, see Exchange admin center in Exchange Online
Help for Office 365 Admins
We're consolidating our content on the Office help and training site. See the following: