Write short notes on POP3.

The POP3 (Post Office Protocol 3) protocol provides a simple, standardized way for users to access mailboxes and download messages to their computers. POP3 holds the email until the user actually receives/downloads the email. When using the POP3 protocol, all the eMail messages get downloaded from the mail server to the user's local computer. The user can choose to leave copies of his/her eMails on the server as well. The advantage is that once messages are downloaded, the user can cut the internet connection and read his/her eMail at own leisure without incurring further communication costs. On the other hand he/she might have transferred a lot of message (including spam and viruses), which may prove dangerous for data on PC.