Hello,
I have an idea to test this. I don't have a mailbox available to test it from my side. Here is the way
- Connect Exchange Online using PowerShell
- Get-CASMailbox 'mailbox name'. Preferably select a test mailbox
- Check the property 'ExternalPopSettings' value. In an environment with POP enabled, this value will show you the server name
- Set this value as False for a test mailbox. Set-CASMailbox 'Mailbox Name' -ExternalPopSettings $Null
- Check if you are able to disable the external access for this test mailbox. Also, restart the POP services to confirm
If it doesn't work, I am sure that there is no way you can selectively disable/enable external Pop access for selected mailboxes and the settings applied to organization wide
Regards,
Manu