Applies to: Exchange Server 2007 SP3, Exchange Server 2007 SP2, Exchange Server 2007 SP1, Exchange Server 2007
Topic Last Modified: 2007-08-14

Microsoft Exchange Server 2007 includes many anti-spam features that depend on downloaded data to determine whether a message can be delivered with confidence that it is not spam.

The following data must be kept up-to-date for the anti-spam features to operate optimally:

Content filter updates These updates contain updated data about phishing Web sites, Microsoft SmartScreen spam heuristics, and other Intelligent Message Filter updates. Content filter updates generally contain about 6 MB of data that is useful for longer periods of time than other anti-spam update data.
Microsoft IP Reputation Service data The Microsoft IP Reputation Service is an IP Block list service that is offered exclusively to Exchange 2007 customers. Administrators can decide to implement and use the Microsoft IP Reputation Service in addition to other real-time block list services.
Spam signature data Spam signatures identify the latest spam campaigns. The spam is hashed into a message digest, or spam signature. This data is used by content filtering to assign a higher spam confidence level (SCL) to known spam. The spam signature files are small. A collection of spam signatures is only a few KB. The spam signatures are also time-sensitive. Therefore, they are updated more frequently than other anti-spam data sets.

Note:
Antivirus functionality typically requires that you update antivirus signature files regularly. Antivirus signature files currently are not included in the anti-spam Automatic Updates functionality.

Anti-spam updates contain data only. They do not contain updated binaries or libraries. Anti-spam updates do not require mail flow interruption or service restarts.

Manual Updates

By default, with manual updates, anti-spam updates are not automatic. Instead, the administrator must visit Microsoft Update to download and install the content filter updates. The content filter update data is updated and available for download every two weeks.

Manual updates from Microsoft Update do not include the Microsoft IP Reputation Service or spam signature data. The Microsoft IP Reputation Service and spam signature data is only available with Microsoft Forefront Security for Exchange Server Anti-spam Automatic Updates. Forefront Anti-spam Automatic Updates is a premium feature that requires either an Exchange Enterprise Client Access License (CAL) for each user mailbox, or a Microsoft Forefront Security for Exchange Server license.

For more information, see How to Manually Update Content Filter Data by Using Microsoft Update.

Automatic Updates

The Automatic Updates client is the application for the Microsoft Windows operating system that communicates with the Windows Update and Microsoft Update Web sites. The Automatic Updates client polls the Windows Update or Microsoft Update Web sites for new updates that are applicable for any of the Microsoft software that is running on the host computer.

You can enable and configure the Automatic Updates client if you visit either the Windows Update or Microsoft Update Web sites. You can configure the Automatic Updates client to download updates automatically, to download and install the updates, or not to download updates. If you configure the Automatic Updates client so that it doesn't download updates, all updates must be performed manually by the end-user of the computer.

Automatic Updates from Microsoft Update do not include the Microsoft IP Reputation Service or spam signature data. Automatic Updates also include all other Windows binary updates, which often require that the user restart the computer. It is not a best practice to configure your Exchange Server to automatically download and install updates from Windows Update.

Forefront Anti-spam Automatic Updates

Forefront Anti-spam Automatic Updates is enabled when you run the Enable Anti-spam Updates wizard or when you run the Enable-AntispamUpdates cmdlet. When you run the Enable Anti-spam Updates wizard, you opt in to use Microsoft Update to help keep the computer that is running Microsoft Exchange up-to-date with anti-spam updates.

Forefront Anti-spam Automatic Updates include all anti-spam updates: the content filter updates, Microsoft IP Reputation Service updates, and the spam signature data. Updates are downloaded multiple times a day. When you enable Forefront Anti-spam Automatic Updates, only the anti-spam data is downloaded. No other data or binaries from the Windows Update service is downloaded or installed with the Forefront Anti-spam Automatic updates.

If you opt in to Forefront Anti-spam Automatic Updates, you must have an Exchange Enterprise CAL for each user mailbox or a Forefront Security for Exchange Server license.

For information about how to enable Automatic Updates, see How to Configure Anti-Spam Automatic Updates.

For More Information

For more information about update services for IT professionals, see Windows Update, Microsoft Update, and Automatic Updates for IT Professionals.
For more information about how to configure Forefront Anti-spam Automatic Updates, see How to Configure Anti-Spam Automatic Updates.
For more information about how to install and configure the Forefront Security for Exchange Server antivirus agent, see Protecting Your Microsoft Exchange Organization with Microsoft Forefront Security for Exchange Server.
For more information about how to manually update the underlying content filter data, see How to Manually Update Content Filter Data by Using Microsoft Update.