Extended Message Properties

Microsoft® Exchange Server 2003 provides connection filtering features such as support for block lists and enterprise-managed Accept and Deny connection lists. Additionally, enterprises can exchange credentials between each other for trusted mail flow.

Connections that are accepted based on authenticated SMTP submission or safe connection address matching continue through the normal connection processing. The spam filter should only be activated for messages that have been submitted anonymously or are not on a safe connection list. The following message properties are available to the content filter to ensure that the filter does not falsely identify e-mail as spam:

• Authentication status. Because the connection is authenticated and, therefore, trusted, spam filters should be designed to allow these messages to bypass spam detection. However, other message processing, such as attachment blocking or virus scanning, can then be applied to these messages.
• Safe connection address status. Because the administrator has configured the system to explicitly accept e-mail from a particular IP address, spam filters should be designed to allow messages from that IP address to bypass spam detection.

You can see example of how to use these properties to determine whether a message should be filtered in the Samplefilter.cpp template file, as described in Template Code Files.