Post Office Protocol (POP)
Post Office Protocol (POP) is a primary protocol for receiving e-mail messages and storing these emails on the recipient’s device. POP also works by integrating itself through a supporting email software client and connects to the remote email server.
It is a protocol of application layer in the OSI model due to which users are able to receive and fetch email messages.
There have been different versions of Post Office Protocol:-
POP1 – Introduced in 1984, specified in RFC 918
POP2 – Introduced in 1985, specified in RFC 937
POP3 -Introduced in 1988, originated with RFC 1081
POP3 is the most commonly used version of the Post Office Protocol. It allows you to download messages on your local device and even being offline you can still read and access the email messages from your device. Once POP3 is used for connecting to the email account, all the email messages get downloaded locally and get deleted from the server this could reduce the space of the email accounts on a Web server.
POP3 works on two ports:-
Firstly, port 110 and secondly, port 995.
port 110 – It is the default non-encrypted POP3 port.
port 995 – It is the port used for securely using POP3. This port uses a secure socket layer (SSL).