Disabling forwarding on opened .msg file

[ti...@247stoke.com]

We have a third party archiving product that returns results as .msg files, which we can then open in Outlook. I'm trying to come up with a solution to prevent these files from being forwarded. I've managed to disable forwarding on an item which exists in my mailbox, but I'm having trouble figuring out how to get outlook to detect an item which doesn't exist in a folder, but has just opened a new message window. Can anyone help?