Restricted Access to External Storage Providers in Outlook on the Web

Step 1:

Connect to Exchange Online PowerShell

You can use the Connect-ExchangeOnline cmdlet to create a PowerShell session to Exchange Online. Both MFA and non-MFA accounts can be connected using the below cmdlet

Connect-ExchangeOnline 

Step 2:

To retrieve the Outlook mailbox policies along with the status of external cloud storage providers, run the following cmdlet

Get-OwaMailboxPolicy | Format-Table Name, AdditionalStorageProvidersAvailable

Before

Output:

Outlook Web App ? Settings (Gear icon) ? Mails ? Attachments ? Storage accounts

Step 3:

To set the Outlook policies to restrict additional storage providers in Outlook, execute the following cmdlet

Set-OwaMailboxPolicy -Identity OwaMailboxPolicy-Default -AdditionalStorageProvidersAvailable $false

After running this command

After

Output:

Also, you can check its enforcement on Outlook web by following the navigation below

Outlook Web App ? Settings (Gear icon) ? Mails ? Attachments ? Storage accounts

The “AdditionalStorageProvidersAvailable” parameter in the above cmdlet will control the access to storage providers in OWA.

To check its effectiveness, run the below PowerShell cmdlet.

Get-OwaMailboxPolicy | Where-Object {!$_.AdditionalStorageProvidersAvailable} | Select-Object -ExpandProperty Name