Microsoft Exchange | Shell | Kalender Settings

First get the current Permissions:

Get-MailboxFolderPermission -Identity MailboxAlias:\Kalender

If you change the Permissions for the first time:

Set-MailboxFolderPermission -Identity MailboxAlias:\Kalender -User AD USER OR GROUP -AccessRights Reviewer

Set-MailboxFolderPermission -Identity MailboxAlias:\Kalender -User AD USER OR GROUP -AccessRights Editor

If you want to add additional Kalender Permissions:

Add-MailboxFolderPermission -Identity MailboxAlias:\Kalender -User AD USER OR GROUP -AccessRights Reviewer

Add-MailboxFolderPermission -Identity MailboxAlias:\Kalender -User AD USER OR GROUP -AccessRights Editor

If you want to add additional Kalender Permissions to all Mailboxes:

foreach ($Mailbox in (Get-Mailbox -ResultSize Unlimited)) { Add-MailboxFolderPermission -identity "$($Mailbox.Name):\Kalender" -AccessRights Editor -User ENTER-HERE-THE-USER }