In this article we will discuss POP Operation – Email protocol, will make brief discussion on POP Operation, In last article we discuss about SMTP Operation.
POP is used by an application to retrieve mail from a mail server. With POP, mail is downloaded from the server to the client and then deleted on the server. This is how POP operates, by default.
The server starts the POP service by passively listening on TCP port 110 for client connection requests. When a client wants to make use of the service, it sends a request to establish a TCP connection with the server. When the connection is established, the POP server sends a greeting. The client and POP server then exchange commands and responses until the connection is closed or aborted. Incoming messages are stored at a POP server until the user logs in (using an email client and downloads the messages to their computer. While SMTP is used to transfer email messages from server to server, POP is used to collect mail with an email client from a server.
With POP, email messages are downloaded to the client and removed from the server, so there is no centralized location where email messages are kept. Because POP does not store messages, it is undesirable for a small business that needs a centralized backup solution. Post Office Protocol version 3 (POP3) is a standard mail protocol used to receive emails from a remote server to a local email client. POP3 allows you to download email messages on your local computer and read them even when you are offline.