Product manual

GFI MailEssentials 2 About GFI MailEssentials | 22
Figure 2: Installing GFI MailEssentials on a mail gateway/relay server
This setup is commonly used to filter spam on a separate machine, commonly installed in the DMZ. In
this environment a server (also known as a gateway/perimeter server) is set to relay emails to the
mail server. GFI MailEssentials is installed on the gateway/perimeter server so that spam and email
malware is filtered before reaching the mail server.
This method enables you to filter out blocked emails before these are received on the mail server and
reduce unnecessary email traffic. It also provides additional fault tolerance, where if the mail server
is down, you can still receive email since emails are queued on the GFI MailEssentials machine.
When installing on a separate server (that is, on a server that is not the mail server), you must first
configure that machine to act as a gateway (also known as “Smart host” or “Mail relay” server). This
means that all inbound email must pass through GFI MailEssentials for scanning before being relayed
to the mail server for distribution. For outbound emails, the mail server must relay all outgoing
emails to the gateway machine for scanning before they are sent to destination.
If using a firewall, a good way to deploy GFI MailEssentials in the DMZ. GFI MailEssentials will act as a
smart host/mail relay server when installed on the perimeter network (also known as DMZ -
demilitarized zone).
Figure 3: Installing GFI MailEssentials on a separate machine on a DMZ