Cross-org free/busy between one -on-prem org and another hybrid org

Hi GarWallis ,

Please try these PowerShell commands,.

Get-Mailbox YourMailbox | fl *sharing*

Get-SharingPolicy -Identity "Default Sharing Policy"

******* Creates the sharing policy "PolicyName" for two different federated domains (ExternalOrg2.com and ExternalOrg1.com) with different sharing actions configured for each domain

New-SharingPolicy -Name "PolicyName" -Domains 'ExternalOrg1.com: CalendarSharingFreeBusyReviewer', 'ExternalOrg2.com: CalendarSharingFreeBusyDetail' -Enabled $True

*********This example modifies the sharing policy for the non-federated Anonymous domain.
This policy allows users in the Anonymous domain to see your users' detailed calendar availability (free/busy) information. .

New-SharingPolicy -Name "Non-Fed_External" -Domains 'Anonymous: CalendarSharingFreeBusyDetail' -Enabled $true

*****************Set SharingPolicy on user
Get-Mailbox -Identity "YourMailbox" | Set-Mailbox -SharingPolicy "PolicyName"

***************Adding a domain to an existing policy (you must include any previously included domains.)

Set-SharingPolicy -Identity "PolicyName" -Domains 'ExternalOrg1.com: CalendarSharingFreeBusySimple', 'ExternalOrg2.com: CalendarSharingFreeBusyReviewer'

Get-Mailbox -ResultSize unlimited | Where {$_.SharingPolicy -eq "PolicyName"} | format-table Alias,EmailAddresses

*********Enable Sharing Policy
Set-SharingPolicy -Identity "PolicyName" -Enabled $True

I hope this is informative.

Regards,

MD