#Bulk convert linked mbx to user mbx (e2k7) using strictly ps.
#Written by Georg Hinterhofer
#Updated by Tony Murray July 2010


#get a list of all linked mbx
$linkedmbx = get-mailbox -resultsize unlimited | where {$_.linkedmasteraccount -match "MYDOMAIN"}


#loop through all mbx
foreach ($mbx in $linkedmbx)
{
#Grab ACL containing AEA property
$AclContainingAEA = $mbx | Get-MailboxPermission | ? {$_.accessrights -like "*ExternalAccount*"}
$ExAccount = $AclContainingAEA.User

$LDAPPath = "LDAP://" + $mbx.DistinguishedName
$object = [ADSI]"$LDAPPath"
    $objectsidh = $object.sIDHistory.value
    If (!$objectsidh) 
    {
        write-host "sIDHistory is blank"
    }
    Else
    {
        write-host "sIDHistory is present" 
        $objectsidh = $Object.getex(“sidhistory”)
        trap
            {
            #write-host "Error doing getex: $_"
            continue
            }
        foreach($sid in $objectSidh)
        {
        #Fix AEA in AD
        $sidh = new-object System.Security.Principal.SecurityIdentifier $sid,0
        write-host "About to remove $sidh"
        Remove-MailboxPermission -Identity $mbx.DistinguishedName -User "$sidh" -AccessRights ExternalAccount -confirm:$false
        }
    }

#Fix MsExchRecipientType in AD so that Box is displayed as User and no longer as linked (change from 2 to 1)
$object.put("msExchRecipientTypeDetails",1)

#Fix msExchMasterAccountSID (clear in AD) so that "isLinked" and "linkeMasterAccount" gets cleared.
$object.putex(1,"msExchMasterAccountSid",$null)

#Save information to AD
$object.setinfo()
}