Amazingly there are still many companies out there today who still manage to forget to close off their Exchange server’s native ability to provide a full open relay.
So just a quick note for you, a very easy way to make sure you aren’t an open relay is to run the following command from the Exchange Management Shell.
Get-ReceiveConnector “ReceiveConnectorName” | Remove-ADPermission -User “NT AUTHORITY\ANONYMOUS LOGON” -ExtendedRights “ms-Exch-SMTP-Accept-Any-Recipient”
Don’t forget to replace ReceiveConnectorName with the name of your own receive connector.
That is it, couldn’t be easier, don’t let your system become a spammer!
There are a number of online tools that can help you to check the status of your server to see if you are an open relay or not, I typically use MXToolbox.
