In order to make sure your Icewarp server is configured to protect against backscatter please follow the steps below.

1.  Open the administration console or webadministration interface

2.  Navigate to the [Mail, General, Delivery] tab

3.  You will now see the drop down labeled "Bounce Back Messages"

4.  Choose "Local Senders Only"

5.  Save your changes

This will now tell the server that bounces are only to be sent if the message originated from a local recipient and thus would no longer be open to sending backscatter to an unknowing recipient who had their email addresses spoofed.