POP3 server authentication
Location: POP3 server settings link in Settings > Site administration > Plugins > Authentication > Manage authentication
POP3 servers
POP stands for Post Office Protocol. This is used to describe how e-mail clients interact with mail servers. The POP3 server is a type of mail server used for incoming mail. In simple terms, POP servers provide a mail-drop service (a temporary mailbox to leave messages so they can be picked up at the recipient's convenience.) When users connect to their ISP POP servers, their e-mail software interface with the server and download any messages for them. POP is only used to receive messages, it is not used to send them. In computing, local e-mail clients use the Post Office Protocol version 3 (POP3), an application-layer Internet standard protocol, to retrieve e-mail from a remote server over a TCP/IP connection. Many subscribers to individual Internet service provider e-mail accounts access their e-mail with client software that uses POP3.
POP3 server authentication
POP3 server authentication is a user authentication process i.e. enabling people to login to your Moodle site.
This method uses the POP3 mail server for the authentication process ie. check for users accounts.