Hi,
I use EFA for a months now and I am very impress about this solution. The server is used with a few internal Exchange 2013 servers to filter all inbound email. It is used too to send outgoing email from Exchange to Internet. I whitelisted each IPs of the internal servers to exclude filtering for my internal users. For some reasons, A few emails out of 15000 are not marked as whitelisted even if the server IP is whitelisted. Those emails go through the filtering process before getting to Internet. I found that emails who got redirected to external recipient are not whitelisted. Even if I exclude them, some emails with many recipients (20+ recipient) are not whitelisted. I double check to be sure they've come from one of my internal server. Is it a normal behavior ?