SetCalendarPermissions.ps1

# Name: SetCalendarPermissions.ps1
# Description: This script sets the default calendar permissions for all users in a Microsoft 365 organization to LimitedRead.
# Author: Alexander Holmeset
# CoContributor: Simon Skotheimsvik, http://skotheimsvik.no, https://x.com/SSkotheimsvik
# Version: 1.0
# Date: 2021-09-01
# Blog: https://alexholmeset.blog
# X(Twitter): https://x.com/AlexHolmeset

# Set the permission level to be set on the calendars.
# Options can be found here:
# https://learn.microsoft.com/en-us/graph/api/resources/calendarpermission?view=graph-rest-1.0#calendarroletype-values

$Permission = "LimitedRead"
  
# Connects to Microsoft Graph with the specified scopes  
Connect-MgGraph -Identity
  
# Generates a list of all users in the Microsoft 365 organization  
$users = Get-MgUser -All -Property "id", "AssignedLicenses", "DisplayName", "Mail", "UserPrincipalName" | Where-Object { $_.AssignedLicenses.Count -gt 0 -and $_.Mail -ne $null}
  
# Sets default access to LimitedRead for all calendars in each user's mailbox  
foreach ($user in $users) {   
  
# Prints the user currently in focus
write-up  
Write-Output "User in focus = $($user.userprincipalname)"   
  
# Initializes the variables to store calendar permissions  
$CalenderPermissions = @()  
$CalenderPermissions = Get-MgUserCalendarPermission -UserId $user.id 
  
# If the user has any calendar permissions, update them  
If($CalenderPermissions){  
$CalenderPermissionsMyOrg = @()  
$CalenderPermissionsMyOrg = $CalenderPermissions | Where-Object {$_.EmailAddress.Name -eq "My Organization"}  
  

  
# Updates the calendar permissions for the user  
If($CalenderPermissionsMyOrg.Role -ne $Permission){
Update-MgUserCalendarPermission -UserId $user.id -Role $Permission -CalendarPermissionId $CalenderPermissionsMyOrg.id
# Prints the user whose calendar permissions are being set  
Write-Output "- Setting permission on calendar for $($user.userprincipalname)"   
}  
Else{  
Write-Output "- Permission already set on calendar for $($user.userprincipalname)"  
}

  

}  
  
}