Understanding SMTP Connections and Commands The process that occurs to establish a connection between a SMTP client and SMTP server is illustrated below: The SMTP client initiates a TCP connection to SMTP server. The SMTP server replies with a ready response – 220 response. The SMTP client sends a helo command to indicate that a SMTP session is to be started. The server returns a response 250. This signifies that the request has been completed. The SMTP client uses the mail from: command to identify the sender of the message. Read More

Exchange Server 2003 uses a number of components, services, and processes that communicate between each other on the local computer and remote computers. The role of the Exchange server and the clients that it has to support determines which services are necessary and unnecessary on your front-end and back-end Exchange servers. All unnecessary services can be disabled. The security of your Exchange Server 2003 system is enhanced when you disable unnecessary services on your Exchange server. Port attacks can no longer be preformed on the ports of disabled services. The Read More