Hi Russell,
yes there is a way to block Office Store, did you try this? See here: https://docs.microsoft.com/en-us/office365/admin/manage/manage-deployment-of-add-ins?view=o365-world...
Prevent add-in downloads by turning off the Office Store across all clients
As an organization you may wish to prevent the download of new Office add-ins from the Office Store. This can be used in conjunction with Centralized Deployment to ensure that only organization-approved add-ins are deployed to users within your organization.
To turn off add-in acquisition:
-
Go to the Office 365 admin center.
-
Click Settings > Services & add-ins.
-
Click Office Store.
-
Click the toggle next to Let people in your organization go to the Office Store so that it's in the Off position.
This will prevent all users from acquiring the following add-ins from the store.
-
Add-ins for Word, Excel, and PowerPoint 2016 from:
-
Windows
-
Mac
-
Office Online
-
iOS
-
Acquisitions starting within AppSource
-
Add-ins within Office 365
A user who tries to access the store will see the following message: Sorry, Office 365 has been configured to prevent individual acquisition of Office Store add-ins.
Support for turning off the Office Store is available in the following versions:
-
Windows: 16.0.9001 - Currently available in monthly channel. Available in semi-annual release in July 2018.
-
Mac: 16.10.18011401 - Currently available.
-
iOS: 2.9.18010804 - Currently available.
-
Office Online - Currently available.
This does not prevent an administrator from using Centralized Deployment to assign an add-in from the Office Store.
best,
Oliver
