manual

Getting Started Guide Installation for Microsoft Exchange 2003  15
3.5 Installing on an email gateway or relay/perimeter server
Introduction
GFI MailEssentials can be installed:
 On a perimeter server (e.g. in a DMZ)
 As a mail relay server between the perimeter (gateway) SMTP
server and the recipients‟ inboxes.
Both setups enable you to reduce unnecessary email traffic by using
your Active Directory resources (at a perimeter/gateway server level)
to drop connections for non-existent email recipients in incoming
email. This helps counter spamming techniques such as Directory
Harvest Attacks (a brute force type of attack used by spammers to find
valid/existent e-mail addresses at a domain). This structure stops the
majority of Spam from arriving at your Microsoft Exchange server.
Figure 3 - A typical Perimeter SMTP Relay Server setup
3.5.1 Upgrades from earlier version
If you are currently using a previous version of GFI MailEssentials
(versions 9, 10, 11, 12 and 14), you can upgrade your current
installation while at the same time retain all your existing configuration
settings.
Important notes
 Upgrades cannot be undone i.e. you cannot downgrade to an
earlier version once you have installed the latest version.
 On upgrading an existing installation, licensing reverts to trial