Microsoft Internet Security and Acceleration (ISA) Server 2004 includes two components to help prevent mail relaying, the entry of viruses, and unwanted attachments on the network. These components are the Simple Mail Transfer Protocol (SMTP) filter and Message Screener. Message Screener is an optional ISA Server component. You can install Message Screener separately from ISA Server and from ISA Server Management.
Using the ISA Server 2004 SMTP Filter and Message Screener discusses when and how to configure the SMTP filter and Message Screener.
The SMTP filter must be configured in the following scenarios:
- You want to adjust the maximum length of an SMTP command that is allowed by the SMTP filter.
- You find a new SMTP command that is vulnerable to attack if the maximum command length is exceeded.
Message Screener must be configured in the following scenarios:
- To block e-mail messages that contain a specific string that is associated with a virus.
- To block e-mail messages that contain a specific attachment, or type of attachment, that is frequently the source of virus infections.
- To block a specific domain that is a source of junk e-mail (spam).
- To block specific outgoing mail.