User Guide

Using Kaspersky SMTP-Gateway application 33
Figure 4. Message processing
5.2.2. General message processing
algorithm
In this section, we describe how Kaspersky SMTP-Gateway processes email
messages. When the server receives an email message AV-module:
1. determines the group this message belongs to.
2. if the message has multiple recipients that belong to different
groups, before further anti-virus scan is performed, the application
creates virtual copies of this message to match the number of
groups and applies different rules to each of such copies.
3. using a built-in MIME format identifier (MIME, RFC822, UUE), the
application divides the message into elements, such as message
body, attachments, etc.
4. if the application is configured to filter objects by name and/or
attachment type, it applies the specified filtering rules for this
message. If the message meets the filter conditions, the object will
be assigned status Filtered and will not be subjected to further
anti-virus scanning.