We have an issue on our hands with emails going out to competitors containing important information.
Currently we're using Google Apps for Business and can easily enough track what happens on all of these Gapps accounts.
What I'd like to be able to do is try to sniff for all email data that leaves our network even if it is sent from someones private address preferably with automatic flagging on certain keywords or attachments.
We have a wide range of tech available to us from linux appliances, cisco's, palo alto gear etc but I am unsure where to start in order to achieve such tracking.
I'm fairly sure this is possible as I've seen full UTM appliances able to sniff through packets to find malicious items so I guess in theory sniffing for email messages would be along the same lines.