I was recently tasked with adding calendar permissions for the members of an AD group to a specific users mailbox. The following Powershell snippet will grant “Editor” permissions on the “someuser” calendar for the members of the AD group named “Some Group”.

This snippet makes use of the Get-ADGroupMember and the Get-Mailbox cmdlets.

Get-ADGroupMember -Identity "Some Group" | ForEach-Object { 
	$mb = Get-Mailbox -Identity $_.distinguishedName
	Add-MailboxFolderPermission -Identity "someuser:\Calendar" -User $mb.Alias -AccessRights Editor