Exchange - Assign Calendar Permissions In Bulk

In my current environment, we have a mix of Shared Mailbox Calendars and calendars shared out by users themselves. While I prefer to use Shared Mailboxes, some departments have high turnover depending on if they contain students and interns so managing calendar perms would be a never ending task for admins.

In this instance, a calendar managed by a user got corrupted (happens a lot on M365 for some reason) and we had to create a new calendar. The problem was, this particular calendar had over 70 users with varying permissions (editor and reviewer). So I needed a way to quickly assign those same perms to the new calendar, without the user having to do it by hand.

You may be asking, why not assign perms by group? Since this is a user-managed calendar, they have no access to AD/groups and with the turnover I mentioned, they add/remove users almost weekly so after the initial assignment, it will be done per user anyway.

As always, PowerShell to the rescue!

First, we'll build a CSV with "Name" as the heading and the list of users like so:

Or if you're copying perms from another calendar, you can export the names and access rights.

In the Exchange Management Shell (EMS) run the following:

Get-MailboxFolderPermission "Buddy Guy:\Calendar\Dept Calendar" | where {$_.accessrights -eq 'editor'} |select user,accessrights | Export-Csv C:\Scripts\caleditors.csv -NoTypeInformation

The above cmdlet will grab all users who have editor rights on the calendar.

Get-MailboxFolderPermission "Buddy Guy:\Calendar\Dept Calendar" | where {$_.accessrights -eq 'reviewer'} |select user,accessrights | Export-Csv C:\Scripts\calreviewers.csv -NoTypeInformation

The above cmdlet will grab all users who have reviewer rights on the calendar.

**Note** Change "Buddy Guy:\Calendar\Dept Calendar" to the user and calendar you're working with and the path and filename you prefer.

Then, format those CSVs like the example above, with just the names.

Next, run the following:

Import-Csv C:\Scripts\caleditors.csv | foreach {add-MailboxFolderPermission -Identity "Buddy Guy:\Calendar\NEW Dept Calendar" -User $_.name -AccessRights Editor}

This will assign editors on the new calendar.

Import-Csv C:\Scripts\calreviewers.csv | foreach {add-MailboxFolderPermission -Identity "Buddy Guy:\Calendar\NEW Dept Calendar" -User $_.name -AccessRights Reviewer}

This will assign reviewers on the new calendar.

**Note** Change "Buddy Guy:\Calendar\NEW Dept Calendar" to the user and new calendar you're working with and path and filename to the where you saved your CSVs.

Now, if you check permissions on the new calendar, you'll see that all of those editors and reviewers have been set. You can run Get-MailboxFolderPermission "Buddy Guy:\Calendar\NEW Dept Calendar" to grab all those perms.

A couple notes to finish up:

Users will still need to manually add the new Calendar to their Outlook.

If running on M365, it *may* take a while for the perms to take effect - I usually tell users to give it a day just to manage expectations - though it will usually work within a few minutes in OWA.

PS. I'll work on a script to copy and apply perms in one shot when I get a chance.