Content Filtering evaluates inbound and outbound email messages on the basis of user-defined rules. Each rule contains a list of keywords and phrases. Content filtering evaluates the header and/or content of messages by comparing the messages with the list of keywords. When the content filter finds a word that matches a keyword, it can take action to prevent the undesirable content from being delivered to Microsoft Exchange clients. The Messaging Security Agent can send notifications whenever it takes an action against undesirable content.
Do not confuse Content Scanning (anti-spam based on signatures and heuristics) with Content Filtering (email scanning and blocking based on categorized keywords). See Content Scanning.
The content filter provides a means for the Administrator to evaluate and control the delivery of email on the basis of the message text itself. It can be used to monitor inbound and outbound messages to check for the existence of harassing, offensive, or otherwise objectionable message content. The content filter also provides a synonym checking feature which allows you to extend the reach of your policies. You can, for example, create rules to check for:
Sexually harassing language
Spam embedded in the body of an email message
By default, content filtering is not enabled.