I have a few Postfix servers that send outbound email through MessageLabs Smarthost. We are now migrating to Mimecast. Of the first 2 servers that I did, I made the same changes, but only 1 of them is sending through Mimecast. Even though the relayhost is the DNS for the Mimecast on both of them, the second is still sending through to message labs. Not sure where else to look. Any thoughts?