User Guide

14 Kaspersky
®
SMTP-Gateway 5.5 for Linux/Unix
Figure 2. The structure of Kaspersky SMTP-Gateway
2. The Receiver module performs preliminary email processing using the
following criteria:
• presence of the sender’s IP address in the list of blocked and/or
trusted addresses including masks
• compliance with the access restrictions specified for SMTP
connections (see section 4.3 on p. 46)
• compliance of the email message size (as well as the mail
session in general and the total number of messages within the
session) with the limits specified in the application settings
• compliance of the number of open sessions (both from all IP
addresses and a single IP address) with the limits specified in
the application settings.
If the message satisfies the preliminary processing requirements, it is
sent to the working queue to be processed by the AV module.
3. The application disassembles each message received from the working
queue into individual components and passes them to the AV module
for analysis.
4. The AV module scans the objects and, if this option is enabled,
disinfects them, when necessary.
5. The application handles messages according to the status assigned to
each object during after the anti-virus scan (blocks message delivery,
deletes infected objects, replaces the original infected objects with
disinfected ones, adds messages to the quarantine directory, etc.).
6. If saving a backup copy in the backup storage or in the quarantine is
specified as the action to be performed on a message, the copy of the
scanned message will be saved in the backup storage or in the
quarantine concurrently with sending it to the ready-to-send queue
(depending on the message status).