The Junk E-mail Filter contains two parts:

• Three Junk e-mail Filter lists: Safe Senders, Safe Recipients, and Blocked Senders.

• State-of-the-art technology developed by Microsoft Research. This technology evaluates whether an unread message should be treated as junk e-mail based on several factors, including the message content and whether the sender is included in Junk E-mail Filter lists.

All settings for the Junk E-mail Filter are stored in each user's Outlook profile. You can override the profile settings by using policies for all options except the Junk E-mail Filter lists. However, you can create and deploy initial lists of Safe Senders, Safe Recipients, and Blocked Senders for your users.

The Junk E-mail Filter is provided for a subset of Outlook account types. The types are listed in the following section, Supported account types. The filter works best when it is used with Microsoft Exchange Server 2003 and later accounts, as described in detail later in this topic.

When Outlook users are upgraded to Office Outlook 2007 , existing Junk E-mail Filter lists are maintained, unless you deploy new lists to users.

Office Outlook 2007 supports junk e-mail filtering for the following account types:

• Microsoft Exchange Server e-mail accounts in Cached Exchange Mode

• Microsoft Exchange Server e-mail accounts when mail is delivered to a Personal Folders file (PST file)

• HTTP accounts

• POP accounts

• MSN Hotmail accounts

• IMAP accounts

The following account types are not supported for Outlook junk e-mail filtering:

• Microsoft Exchange Server e-mail accounts in Online (MDB) mode

• Third-party MAPI providers

Information about what junk e-mail filtering options are available with Exchange Server is included in the next section, Support in different versions of Exchange Server.

In scenarios in which POP e-mail messages are downloaded into an Exchange Online (MDB) mailbox, Outlook blocks junk e-mail messages for the user's POP e-mail; however, Outlook does not block Exchange Online junk e-mail messages.

Junk E-mail Filter behavior depends on the Exchange Server version you use for messaging. Later versions of Exchange Server support more filtering options than earlier versions do.

The following list details Junk E-mail Filter behavior with different versions of Exchange Server.

• Versions earlier than Exchange Server 2003

  If users use Cached Exchange Mode or download to a Personal Folders file (PST file): Users can create and use the Junk E-mail Filter lists, which are available from any computer that users use.

  If users work online: The Junk E-mail Filter is not available.

• Exchange Server 2003 and later versions of Exchange

  If users use Cached Exchange Mode or download to a PST file: The Junk E-mail Filter lists that are available from any computer are also used by the server to evaluate mail. This means that if a sender is on a user's Blocked Senders list, mail moves to the Junk E-mail folder on the server and is not evaluated by Office Outlook 2007. In addition, Office Outlook 2007 uses Microsoft Research technology to evaluate e-mail messages.

  If users work online: The Junk E-mail Filter lists that are available from any computer are also used by the server to evaluate mail. This means that if a sender is on a user's Blocked Senders list, mail moves to the Junk E-mail folder on the server and is not evaluated by Office Outlook 2007.

When a user's previous version of Outlook (earlier than Outlook 2003) is upgraded to Office Outlook 2007, the rules that previously handled junk e-mail messages are removed. The existing rules and files used by the old filter are not migrated. The existing rules are handled as follows:

• Rules created by the old filter

  With the previous rules filter for junk e-mail messages, users could create up to three client-side rules for their mailbox: Adult Content Rule, Junk E-mail Rule, and Exception List.

  Outlook removes these rules from the user's mailbox when Outlook 2003 starts for the first time on the user's computer. This means that Outlook 2003 always disables the previous junk e-mail filter.

• Files that contain the Adult Senders list and the Blocked Senders list

  These text files are left on the user's computer, but Outlook no longer uses the files.

You can specify several options to configure how the Junk E-mail Filter works for your users, including the following:

• Set the Junk E-mail Filter protection level.

• Permanently delete suspected junk e-mail messages or move the messages to the Junk E-mail folder.

• Trust e-mail messages from users' Contacts.

The default values for the Junk E-mail Filter are designed to help provide a positive experience for users. However, you can configure these settings to different defaults and set other options and policies when you deploy Outlook to your organization, such as defining an alternative URL for the location of filter updates.

Junk e-mail settings are set only once. When the user first starts Outlook 2003, the settings are configured in the profile that the user chooses. Other profiles the user has, or may create later, do not include the settings that you have configured. Instead, default settings are used.

Default values for the Junk E-mail Filter settings are:

• Junk E-mail: Set to LOW

• Permanently delete: Set to OFF

• Trust my Contacts: Set to ON

You can use the Office Customization Tool to configure these options to specify default values for users, or the options can be enforced by Group Policy. For more information about configuring options for the Junk E-mail Filter, see Configure junk e-mail settings in Outlook 2007.

You can deploy default Junk E-mail Filter lists to your users. The Junk E-mail Filter uses these lists as follows:

• Safe Senders list

  E-mail messages received from the e-mail addresses in the list or from any e-mail address that includes a domain name in the list are never treated as junk e-mail.

• Safe Recipients list

  E-mail messages sent to the e-mail addresses in the list or to any e-mail address that includes a domain name in the list are never treated as junk e-mail.

• Blocked Senders list

  E-mail messages received from the e-mail addresses in the list or from any e-mail address that includes a domain name in the list are always treated as junk e-mail.

If a domain name or e-mail address is on both the Blocked Senders list and the Safe Senders list, the Safe Senders list takes precedence over the Blocked Senders list. This reduces the risk that mail that users want might be treated as junk e-mail by mistake. The lists are stored on the server and are available if users roam.

To deploy the Junk E-mail Filter lists, you create the lists on a test computer and distribute the lists to your users. The lists you provide are default lists; they cannot be locked down by policy. For more information about deploying default lists, see Create and deploy Junk E-mail Filter lists in Outlook 2007.

This topic is included in the following downloadable books for easier reading and printing:

• Messaging guide for the 2007 Office release

• Planning and architecture for the 2007 Office release

• Security for the 2007 Office release

See the full list of available books at Office Resource Kit information.

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