User Guide

CHAPTER 2. APPLICATION
STRUCTURE AND TYPICAL
DEPLOYMENT SCENARIOS
Correct application setup and its efficient operation require knowledge of its
structure and internal algorithms. It is also important for application deployment
within an existing corporate email system. This chapter contains a detailed
discussion of the application’s structure, architecture and operating principles as
well as typical scenarios of its deployment.
2.1. Application architecture
The review of the application functionality must be preceded by a description of
its internal architecture.
Kaspersky SMTP-Gateway is a full-featured Mail Transfer Agent (MTA) able to
receive and route email traffic scanning email messages for viruses.
Kaspersky SMTP-Gateway uses SMTP protocol commands (RFC 2821), Internet
message format (RFC 2822), MIME format (RFC 2045-2049, 2231, 2646), and
satisfies the requirements to mail relays (RFC 1123). In compliance with anti-
spam recommendations (RFC 2505 standard), the application employs access
control rules for SMTP clients to prevent the use of this application as an open
relay. In addition, Kaspersky SMTP-Gateway supports the following SMTP
protocol extensions:
• Pipelining – enhances performance of servers supporting this mode of
operation (RFC 2920).
• 8-bit MIME Transport – processes national language characters code
tables (RFC 1652).
• Enhanced Error Codes – provides more informative explanations of
protocol errors (RFC 2034).
• DSN (Delivery Status Notifications) – decreases bandwidth usage and
provides more reliable diagnostics (RFC 1891, 3461-3464).
• SMTP Message Size – decreases the load and increases transfer rate
(RFC 1870).