POP3 is an application layer Internet standard protocol used to retrieve e-mail from a remote server to a local client over an Internet connection.
Nearly all individual Internet service provider (ISP) e-mail accounts are accessed via POP3.
In contemporary usage, the less precise term POP almost always means POP3 in the context of e-mail protocols.
Although most e-mail applications (such as Outlook Express, Netscape Mail, and Mozilla) have an option to leave mail on the server, e-mail applications using POP3 generally connect, retrieve all messages, store them on the user's PC as new messages, delete them from the server, and then disconnect.
Since POP3 transfers the entire pending queue of new mail messages, any attachments are downloaded before proceeding on to subsequent messages.
When using POP3, we highly recommended that you do NOT leave mail on the server.
If you need to leave messages on the server, you should enable the account properties to remove them from server after a set period of time.
The following are instructions for viewing/changing this setting.
(Please refer to your product's help feature for additional information.)