Complete the Office 365 guided setup using the custom configuration option.
Verify That Ports Are Open
Verify that the required ports are open.
Go the Office 365 Guided Setup
From the navigation pane, go to Guided setup.
The Welcome page appears.
On the Protect tab, click Office 365.
The Office 365 setup appears.
Create a Server Plan That You Can Use for Exchange Online
If you already have a server plan that you can use, you can skip this step.
On the Create server backup plan page, specify the settings for a server plan that you can use for the Exchange Online app.
Folders to back up
Create an Office 365 App for Exchange Online
On the Add Office 365 app page, specify the settings for the Exchange Online app that will contain the mailboxes that you want to back up.
Exchange connection settings