Pine is an IMAP (Internet Message Access Protocol) client and POP (Post Office Protocol) client which can access local VMS MAIL mail files as well as other mail files served by an IMAP server or POP3 server.
If only local mail is to be accessed, no network connection is created, and no IMAP server or POP server is needed on the local system. If your system does not have any TCP/IP software installed, then you will receive an error message when you attempt any operation requiring TCP/IP access. To access mail files on a remote OpenVMS system, an IMAP server such as the PMDF IMAP server, or a POP server such as the PMDF POP server, must be running on that remote system. To access mail files on a remote UNIX system, the remote system must have an IMAP daemon (server) or POP daemon (server) running.2
Pine is also an NNTP (Network News Transport Protocol, RFC 977) client, and can be used to read news from NNTP servers like the ANU News program or many common UNIX NNTP servers. Of course, you have to know the name of one such system before you can use this capability. Ask your system or network manager for help.
The pine view is that messages are stored in folders, and folders are stored in folder collections. Folder collections can be physically located on the local system, or on any remote system with an IMAP server. Regardless of what system a folder collection is physically located on, a pine user sees it as just another folder collection: a pine user can read messages in any of their folder collections and can save (move) messages between different folder collections. See Section 7.4 below for more details on folders and folder collections.
Or a read-and-delete-only pine folder can correspond to the "new messages" folder on a remote system with a POP3 server. (The POP3 protocol does not provide access to multiple folders---it only provides access to the "new" messages, usually those in a special "new" sort of folder. The POP3 protocol also does not allow for moving messages into a POP3 folder.)
2 To find out more about IMAP, read the IMAP4rev1 specification stored in the file PMDF_ROOT:[DOC.RFC]RFC2060.TXT; to find out more about POP, read the POP3 specification stored in the file PMDF_ROOT:[DOC.RFC]RFC1939.TXT.