RFC 937 (rfc937) - Page 2 of 24
Post Office Protocol: Version 2
Alternative Format: Original Text Document
RFC 937 February 1985 Post Office Protocol we expect the user's mail to be addressed to JSmith@DOG-HOUSE.ARPA (not JSmith@FIDO.ARPA). That is, the destination of the mail is the mailbox on the server machine. The POP2 protocol and the workstation are merely a mechanism for viewing the messages in the mailbox. The user is not tied to any particular workstation for accessing his mail. The workstation does not appear as any part of the mailbox address. This is a very simple protocol. This is not a user interface. We expect that there is a program in the workstation that is friendly to the user. This protocol is not "user friendly". One basic rule of this protocol is "if anything goes wrong close the connection". Another basic rule is to have few options. POP2 does not parse messages in any way. It does not analyze message headers (Date:, From:, To:, Cc:, or Subject:). POP2 simply transmits whole messages from a mailbox server to a client workstation. The Protocol The POP2 protocol is a sequence of commands and replies. The design draws from many previous protocols of the ARPA-Internet community. The server must be listening for a connection. When a connection is opened the server sends a greeting message and waits for commands. When commands are received the server acts on them and responds with replies. The client opens a connection, waits for the greeting, then sends the HELO command with the user name and password arguments to establish authorization to access mailboxes. The server returns the number of messages in the default mailbox. The client may read the default mailbox associated with the user name or may select another mailbox by using the FOLD command. The server returns the number of messages in the mailbox selected. The client begins a message reading transaction with a READ command. The read command may optionally indicate which message number to read, the default is the current message (incremented when a message is read and set to one when a new folder is selected). The server returns the number of characters in the message. Butler, et. al.
