SMTP is an application layer protocol. The client who wants to send the mail opens a TCP
SMTP is an application layer protocol. The client who wants to send the mail opens a TCP connection to the SMTP server and then sends the mail across the connection. The SMTP server is always in listening mode. As soon as it lists a TCP connection from any client, the SMTP process initiates a connection on that port (25). After successfully establishing the TCP connection the client process sends the mail instantly.
Describe the protocol and explain in detail why is this protocol good and which component (Host / Client / Server / Firewall / Router / Switch / Hot Spot) on the network needs it most and uses it?