POP Client Control

The POP Client control implements the POP3 Protocol Client as specified by RFC 1081, Post Office Protocol.

Remarks

The POP control provides access to Internet mail servers using the POP3 protocol. It can be used by Internet mail developers or system integrators. The major advantage of this control is its ability to retrieve mail from UNIX or other servers supporting the POP3 protocol.

The main features of the POP control are that it:

• Connects to a server.
• Sends authentication information (user and password) to the server.
• Retrieves user mailbox information, such as the number of messages waiting to be retrieved.
• Retrieves messages from the server.
• Deletes messages from the server.

POP3 Commands

The following table summarizes POP3 commands. All the commands are implemented in the control, although some of them are abstracted at a higher level (e.g. USER + PASS = Authorization).

Command	Usage	When Valid
DELE msg	required	TRANSACTION state
LAST	required	TRANSACTION state
LIST [msg]	required	TRANSACTION state
NOOP	required	TRANSACTION state
PASS string	required	AUTHORIZATION state
QUIT	required	AUTHORIZATION and UPDATE state
RETR msg	required	TRANSACTION state
RPOP user	optional	AUTHORIZATION state; not supported in current release
RSET	required	TRANSACTION state
STAT	required	TRANSACTION state
TOP msg n	optional	TRANSACTION state; supported if it is supported by the server.
USER name	required	AUTHORIZATION state

Each of the POP3 commands can return either:

• +OK
• ERR

The reply given by the POP3 server to any command is significant only up to "+OK" and "-ERR". The client can ignore any text occurring after this reply. The only exception is the STAT command.

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