Premise Based Software
When it comes to filtering business email SPAM, you have a few options. Each option has its unique set of advantages and disadvantages – what you choose will likely depend on your preferences and the amount of time and effort you want to put into this project.
This option is what you would call a traditional filter. A piece of software is installed on your email server which scans incoming mail for SPAM and viruses. Anything it catches is placed into quarantine or deleted depending on your preferences. Premise based software is typically licensed per user or mailbox. The advantage of using premise based software is that it doesn’t require any additional hardware. You install the package on your mail server under most circumstances and manage the package through a client or web based interface. The downside is a higher risk for letting viruses or SPAM on your network. Since the email and quarantine are stored on the mail server, these malicious items could potentially make their way onto other machines. It may be unlikely, but something to consider.
Popular software vendors for premise based software are Symantec, Microsoft and Trend Micro.
Premise Based Appliance
Appliances act as a mail gateway for your organization. Mail is delivered to the appliance, is tested and then either quarantined, deleted or forwarded on to your mail server. Appliances are an attractive option since they typically require very little maintenance and are thought of as being more secure than a software component installed on your mail server.
Appliances are typically licensed per mailbox, although some devices, like the Barracuda SPAM Filter, do not have any per user licensing. Downsides to using the appliance approach are few – it is another box to manage and requires a bit more knowledge on your part to set up the proper mail exchange (mx) and DNS records, but the extra protection you get and the fact these machines are built for simple administration make it highly recommended. Popular appliance vendors are Barracuda Networks, St. Bernard Software and McAfee.
Hosted solutions are quickly becoming very popular. It combines the ease of managing an appliance without needing to spend the upfront costs of an appliance based product. Hosted solutions act as a gateway in that incoming mail goes to your hosting provider, gets scanned and then forwarded on to your mail server. Hosted solutions cost less up front and are charged on a monthly basis for the number of mailboxes you have.
The downside to hosted solutions is that you are entrusting your hosting provider with taking care of your email before it gets to you. Top tier providers can easily overcome this fear with much more robust systems and redundancy than you probably have at your location. In this case, the hosted provider could potentially act as a backup location for your email.
Popular hosted products include Messagelabs and Postini.
If at all possible, I would recommend implementing two levels of protection. No single SPAM filter will catch 100% of SPAM so it’s beneficial to have two systems in place to increase the likelihood of catching most of the SPAM. Consider implementing one of the two gateway products (an appliance or hosted filtering) and a local solution installed on your mail server. This will offer you the highest level of protection.