Если 2012 можно через через PowerShell

$ConnectionBroker = ""
$SessionHostCollection = "Терминал"

$MessageTitle = "От кого)) "
$MessageText = "Текст "

If ($ConnectionBroker -eq "") {
$HAFarm = Get-RDConnectionBrokerHighAvailability
$ConnectionBroker = $HAFarm.ActiveManagementServer
}

$Sessions = Get-RDUserSession -ConnectionBroker $ConnectionBroker -CollectionName $SessionHostCollection
ForEach ($Session in $Sessions) {
Send-RDUserMessage -HostServer $Session.ServerName -UnifiedSessionID $Session.UnifiedSessionID -MessageTitle $MessageTitle -MessageBody $MessageText
}

Active Directory Sites and Services - Sites -Inter-Site Transports - IP А там навастриваете линки как Вам надо.

Я думаю лучше решение использовать - WDS

Может стоит использовать RemoteApp