The Post Office Protocol 3 (POP3) is an email protocol for receiving mails from a remote mail server to a local mail client. It supports downloading and deleting messages from a remote mail server.
POP3 is designed to delete mail on the server as soon as the user has downloaded it. However, some implementations allow users or an administrator to specify that mail be saved for some period of time. POP3 can be thought of as a "store-and-forward" service.
An alternative protocol is Internet Message Access Protocol (IMAP). IMAP provides the user more capabilities for retaining e-mails on the server, organizing it in folders, and accessing the mails using webmail clients or several different email clients on different devices.