One of the first things you have to do when deploying a Secure Email Gateway like Mimecast or Proofpoint is change your MX Records. Mail Exchange (MX) records are necessary for the delivery of all emails.
When using an SEG, enterprises have to change their MX records to that of the Gateway.
By doing this, a few negative things happen:
When installing a solution like Avanan, which doesn't switch, you'll see the following major benefits:
When you don't change your MX records to that of the gateway, you benefit from being far safer.