6.1 Core SMTP transport

Windows 2000 Server includes a functional Simple Mail Transfer Protocol (SMTP) component to provide a reliable transport mechanism for the Windows 2000 operating system and for applications layered on Windows 2000. This SMTP component runs as part of the inetinfo.exe process and supports many of the Extended SMTP (ESMTP) standards. Messages can be submitted to the Windows 2000 SMTP using the SMTP protocol through port 25, using a drop-off directory for properly formatted e-mail messages, or using Collaboration Data Objects (CDO).

The Windows 2000 SMTP component also supports the transport and protocol sinks that allow programmers to extend the capabilities of the basic SMTP component. Exchange takes advantage of these transport and protocol sinks to extend the basic SMTP functionality. When you install Exchange 2000, it adds SMTP extensions in the following areas:

• Adds an Exchange Installable File System (IFS) store driver that allows message pickup and drop-off directly from the Information Store without having to queue the messages in specific Windows 2000 file system directories.

• Adds an Advanced Queuing Engine to manage message delivery queues.

• Adds an enhanced message categorization agent that examines messages and queues the message for delivery based on certain message attributes. Windows 2000 includes a basic message categorization agent (cat.dll). The Exchange categorization agent (humorously named phatcat.dll ) includes support for Exchange-specific attributes.

• Adds routing engine support for using link state status information to make intelligent routing decision based on the most current network conditions.

• Adds SMTP command...