Create method to create organisation wide safe sender list that displays on the mailbox junk email configuration safe senders List
Currently there is no good way to deploy safe sender lists to Outlook client users. The GPO method used in Outlook only works if users are connected to the corporate network. In a world where more users WFH safe sender lists are not being published correctly. The exchange powershell option of set-mailboxJunkEmailConfiguration allows the setting of safesender lists but 1) does not allow own domain addresses to be added and 2) is not designed for Organization wide deployment as you need to import the mailboxes to the command.
Dominik Dünnebacke commented
Kudos. Also considering that users are able to add internal email addresses to blocked senders in OWA. As an admin we should be able to either prevent or override this centrally.