An email gateway (a.k.a. firewall) is a machine (physical or virtual) installed between Internet and the email server. Its primary role is to protect the email server by filtering incoming messages, via SMTP protocol, from Internet. Secondary, an email gateway may be used as an outgoing gateway in case you want to add some new email features which are not provided by older email servers. For instance, Exchange 2000 or 2003 has no DKIM signing and verification service – a quality improvement for message delivery. This tutorial shows how to configure an email gateway with the Scrollout F1 email gateway.