I recently encountered the following error when attempting to update the default antispam policy GUI (https://security.microsoft.com/antispam) for a new client’s Exchange 365 tenant:
“…The command you tried to run isn’t currently allowed in your organization. To run this command, you first need to run the command Enable-OrganizationCustomization.”
So, I fired up an instance of Exchange Online PowerShell and tried to run the Enable-OrganizationCustomization cmdlet…
…but I was told it was already enabled!
“This operation is not required. Organization is already enabled for customization.”
If the CLI was insisting that Organization Customization was already enabled, who was I to argue? So, I switched gears and attempted to implement the change through PowerShell instead:
Set-HostedConnectionFilterPolicy -Identity Default -IPAllowList [IP Address]
Not only did this work, but the change was also reflected in the GUI! Subsequent changes through the GUI were also successful (i.e., no more prompts to enable Organization Customization).