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From: taylor@hplabsc.UUCP (Dave Taylor)
Newsgroups: net.news.b
Subject: POP2 (RFC937) comments...
Message-ID: <22000002@hplabsc.UUCP>
Date: Fri, 11-Apr-86 16:52:00 EST
Article-I.D.: hplabsc.22000002
Posted: Fri Apr 11 16:52:00 1986
Date-Received: Sun, 13-Apr-86 08:42:12 EST
Organization: Hewlett-Packard Laboratories - Palo Alto, CA
Lines: 63



	Comments on the Post Office Protocol, Version 2

			(aka RFC-937)

  First off, I think this is a very reasonable protocol and has the
advantage of being SIMPLE and easy to implement (a big plus).  There
are, however, a few problems in the document, namely;

	1. It's not clear whether the request for a specific
	   message to be transmitted (ie READ nnn) will be
	   interpreted as relative to the Beginning of the 
	   folder/mailbox or relative to the current message

	2. At one point the document indicates that the client
	   transmits a "RETR" command with the server immediately
	   responding with the message data.  Later on, however,
	   it is stated that the RETR "must be followed by an
	   acknowledgement command".  Perhaps the problem is that
	   the quoted sentence should be changed to read something
	   more like "the RETR command, with the server immediately
	   transmitting the message.  Completion of this transaction
	   must be acknowledged by the client."

	3. For lack of confusion, I suggest that arguments like "user"
	   (login account name) and so on are either delimited by a
	   different type face (ideally italicized) or surrounded by
	   metacharacters as in "/usr/<user>"...

	4. The default mailboxes for Unix are strange.  Specifically, I've 
	   never heard of any Unix system that queues mail in 
	  	/usr/<user>/Mail/inbox/*
	   On the other hand, "/usr/mail/<user>" is quite common on Bell
	   systems...

	5. The FOLD command should have "- error report" added as a
	   possible response by the server.  Otherwise, how does the
	   client learn that the requested access has been denied?

	6. If the client requests a deletion of a message (ACKD) and 
	   permission is denied, how is this indicated?

	7. Why does a RETR of 0 characters terminate the connection??

	8. In the sequence RETR 2 ; <send> ; ACKD ; RETR 1 ; <send> ; ACKS
	   the return should be different from the sequence HELO a b ; #1 ;
	   RETR ; < send > ; ACKS.  That is, the return should distinguish
	   between no-more-messages and next-message-marked-as-deleted.
	   (In fact, in the latter case, perhaps the ACK* should increment
	   the current-message to the next UNDELETED message or EOF, which-
	   ever comes first)

	9. In a more general sense, it would be interesting to have a
	   similar protocol for queueing OUTBOUND messages too...(to be
	   distinguished from the UUCP wait-till-it-calls-us method)

  I await responses from either the original POP2 team or anyone else who
knows the protocol.

					-- Dave Taylor

				taylor@HPLABS   -or-   hplabs!taylor