<?xml version="1.0" encoding="utf-8" ?>
<Configuration version="1.0">
<Feature Name="MailboxProvisioning" Cmdlets="new-mailbox,enable-mailbox">
<ApiCall Name="OnComplete">
if($succeeded) {
start-sleep -s 5
Set-ADServerSettings -ViewEntireForest $true
$mailbox = [string]$provisioningHandler.UserSpecifiedParameters["Identity"]
$Folder = ":\Calendar"
$Root = ":\"
$UserAndFolder = $mailbox + $Folder
$UserAndRoot = $mailbox + $root
add-MailboxFolderPermission -Identity $UserAndFolder -User "adamh" -AccessRights author
add-MailboxFolderPermission -Identity $UserAndRoot -User "adamh" -AccessRights foldervisible
}
</ApiCall>
</Feature>
</Configuration>

----

#No Account

[PS] C:\Windows\system32>get-mailbox fowler
The operation couldn't be performed because object 'fowler' couldn't be found on 'DC01.CORP.WHYADMIN.COM'.
    + CategoryInfo          : NotSpecified: (:) [Get-Mailbox], ManagementObjectNotFoundException
    + FullyQualifiedErrorId : 23B091B0,Microsoft.Exchange.Management.RecipientTasks.GetMailbox
    + PSComputerName        : mbx01.corp.whyadmin.com


#Create Account
[PS] C:\Windows\system32>enable-mailbox fowler

Name                      Alias                ServerName       ProhibitSendQuota
----                      -----                ----------       -----------------
Fowler Mc. Fowler         fowler               mbx01            Unlimited

#Check Permissions

[PS] C:\Windows\system32>Get-MailboxFolderPermission fowler:\calendar

FolderName           User                 AccessRights
----------           ----                 ------------
Calendar             Default              {AvailabilityOnly}
Calendar             Anonymous            {None}
Calendar             Adam Hubbard         {Author}


[PS] C:\Windows\system32>Get-MailboxFolderPermission fowler:\

FolderName           User                 AccessRights
----------           ----                 ------------
Top of Informatio... Default              {None}
Top of Informatio... Anonymous            {None}
Top of Informatio... Adam Hubbard         {FolderVisible}