In Exchange 2007, anti-spam processing’s performed by a series of Transport Agents. All Exchange 2007 anti-spam Transport Agents, except for Attachment Filtering, are enabled during SBS Setup. Because Attachment Filtering is only available on Edge Transport role, SBS 2008 gives you option to install a 120 day trial version of Forefront Security for Exchange during setup, which provides this service as well as anti-virus processing. Out of box, SBS 2008 offers strong protection against spam while minimizing false positives. However, it’s open to customization as determined by needs of your organization. Following is an example of Exchange PowerShell command Get-TransportAgent from a default installation of SBS 2008. NOTE: Transport Rule Agent, Journaling Agent, and AD RMS Prelicensing Agent are configured by default but don’t perform anti-spam processing. SBS 2008 also configures Exchange to automatically update anti-spam Transport Agents from Microsoft Update. New versions are published every two weeks. This process occurs independently of WSUS.
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