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54  Installation for Microsoft Exchange 2007 & 2010 Getting Started Guide
Screenshot 48 - Server roles detected and list of components to install.
7. A list of the Microsoft Exchange Server 2007/2010 server roles
detected and GFI MailEssentials components required is displayed.
Click Next to install the required GFI MailEssentials components.
8. Click Finish to finalize the installation.
The GFI MailEssentials installation is now complete and the anti-spam
system is up and running. For more information about how to optimize
GFI MailEssentials refer to Post-install actions chapter.
4.5 Installing on an email gateway or relay/perimeter server
Introduction
GFI MailEssentials can be installed:
 On a perimeter server (e.g. DMZ) with Microsoft Exchange Server
2007/2010 in Edge Server role.
 As a mail relay server between the perimeter (gateway) SMTP
server and the recipients‟ inboxes with Microsoft Exchange Server
2007/2010 in Hub Transport role.
Both setups enable you to reduce unnecessary email traffic by using
your Active Directory resources (at a perimeter/gateway server level)
to drop connections of non-existent email recipients in incoming email.
This greatly helps against common 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 eliminates most spam from arriving at your Microsoft
Exchange server.