List all Microsoft Booking Calendars

If you’re using Microsoft Booking in your Microsoft 365 Tenant, you might want to list all of the Booking calendars. Booking uses Exchange Online Mailboxes in the background. Every Booking Calendar has a corresponding Mailbox of the type “SchedulingMailbox”. If an user gets assigned “Administrator” for a Booking Calendar, they get “FullAccess” permissions for the Scheduling Mailbox.

List all Booking Calendars with permission

I wrote a PowerShell script to list all the Booking Mailboxes with the users that have access.

# prerequisite: Exchange Online v2 PowerShell module, must be connected to the service

$BookingsMailboxesWithPermissions = New-Object 'System.Collections.Generic.List[System.Object]'
# Get all Booking Mailboxes
$allBookingsMailboxes = Get-ExoMailbox -RecipientTypeDetails SchedulingMailbox -ResultSize:Unlimited

# Loop through the list of Mailboxes
$BookingsMailboxesWithPermissions = foreach($bookingsMailbox in $allBookingsMailboxes) {
    # Get Permissions for this Mailbox
    $allPermissionsForThisMailbox = Get-ExoMailboxPermission -UserPrincipalName $bookingsMailbox.UserPrincipalName -ResultSize:Unlimited | Where-Object {($_.User -like '*@*') -and ($_.AccessRights -eq "FullAccess")}
    foreach($permission in $allPermissionsForThisMailbox) {
        # Output PSCustomObject with infos to the foreach loop, so it gets saved into $BookingsMailboxesWithPermissions
        [PSCustomObject]@{
            'Bookings Mailbox DisplayName' = $bookingsMailbox.DisplayName
            'Bookings Mailbox E-Mail-Address' = $bookingsMailbox.PrimarySmtpAddress
            'User' = $permission.User
            'AccessRights' = "Administrator"
            }
    }
}
$BookingsMailboxesWithPermissions | Export-Csv C:\temp\bookings-permissions.csv -Encoding utf8 -Delimiter ";" -NoTypeInformation   

Example of result:

In this case, there are two Booking Mailboxes in the tenant. One of the Mailboxes has two “Administrators” assigned.

"Bookings Mailbox DisplayName";"Bookings Mailbox E-Mail-Address";"User";"AccessRights"
"Our Calendar";"[email protected]";"[email protected]";"Administrator"
"Our Calendar";"[email protected]";"[email protected]";"Administrator"
"Test";"[email protected]";"[email protected]";"Administrator"   

List all Booking Calendars

If you only want to list the calendars, replace the last line of the script with the following:

$BookingsMailboxesWithPermissions | Sort-Object -Property "Bookings Mailbox E-Mail-Address" -Unique | Export-Csv C:\temp\bookings-permissions.csv -Encoding utf8 -Delimiter ";" -NoTypeInformation