As a channel reseller, some of your customers probably count on you to make server hardware recommendations. If a customer follows your recommendations and receives sub-par performance from a recently purchased server, you will lose credibility with that customer. Therefore, it is sometimes advantageous not only to recommend hardware that is capable of handling the anticipated workload, but also to take steps to reduce the server's workload and increase the server's reliability.
Organizations running Exchange Server are a perfect example of this concept. Typically, Exchange Servers are bombarded day in and day out by spam, email viruses, phishing scams, and just about any other type of undesirable mail that you can imagine. These types of messages are not only a nuisance, they also rob a mail server of performance. One way to get some of that performance back is to filter inbound SMTP messages before they reach the Exchange Server. By directing inbound SMTP traffic to a Microsoft Internet Security and Acceleration (ISA) Server first, you can nab certain types of malicious email messages before they reach the Exchange Server. This will not only improve email security, it will also improve performance because you are reducing the overall volume of SMTP mail that the Exchange Server must process.

How to use an ISA Server as an SMTP filter

Introduction
Install the SMTP service
Configure the Internet Information Server
Install ISA Server 2004
Create an SMTP publishing rule
Create a DNS publishing rule
Configure the message screener
Change your DNS server's MX record
About the author
Brien M. Posey, MCSE, is a Microsoft Most Valuable Professional for his work with Windows 2000 Server and IIS. Brien has served as the CIO for a nationwide chain of hospitals and was once in charge of IT security for Fort Knox. As a freelance technical writer he has written for Microsoft, TechTarget, CNET, ZDNet, MSD2D, Relevant Technologies and other technology companies.