[EAI] #1483 draft-ietf-eai-smtpext-06.txt 2.7.4. UTF-8 Reply

[Kari Hurtta <hurtta+gmane at siilo.fmi.fi>]

Harald Tveit Alvestrand <harald at alvestrand.no> writes in gmane.ietf.ima:

> The following tickets are open on the EAI issue tracker:
> 
> 1483 SMTPEXT 2.7: Non-ASCII in response texts Text proposed in -06, no
> later discussion.

I suggest small change to text. Change here is on diff format.
Dicussion follows.

---------------------------------------------------------------------------
--- draft-ietf-eai-smtpext-06.txt	2007-06-05 06:40:53.000000000 +0300
+++ draft-ietf-eai-smtpext-06.txt--1483	2007-06-16 09:16:28.000000000 +0300
@@ -600,18 +600,26 @@
    MUST be transmitted in the form of ACE labels.  The protocol value of
    the WITH clause is UTF8SMTP when this extension is used.  More
    information is in the "IANA Considerations" section of this document.
 
 2.7.4.  UTF-8 Reply
 
-   If the client issues the "RCPT" command which contains non-ASCII
+   If the client issues the RCPT command which contains non-ASCII
    characters, the SMTP server is permitted to use UTF-8 characters
    within 251 and 551 response codes.  Servers MUST NOT include non-
    ASCII characters except in the limited cases specifically permitted
-   in this section.
+   in this section. The SMTP client following this specification MUST 
+   accept UTF-8 on replies of the RCPT command on that case.
 
+   If SMTP reply requires UTF-8, but SMTP client does not use
+   RCPT command which contains non-ASCII characters, the response
+   code 250 meaning "OK"  or 550 meaning "Requested action not taken:
+   mailbox unavailable" is used.  When response codes 250 and 550 is 
+   used on place of 251 and 551 response codes, response do not include 
+   new mailbox. If enhanced mail system status code [RFC3463]
+   is used,  response codes given on below is used.
 
 
 Yao & Mao               Expires December 8, 2007               [Page 11]
 
 Internet-Draft                     EAI                         June 2007
 
@@ -627,28 +635,26 @@
    is included in it and therefore UTF-8 is not needed.  UTF8REPLY
    parameter on the VRFY and EXPN commands tells the SMTP server that
    the client is prepared for UTF-8 on SMTP replies.
 
    VERIFY (VRFY) and EXPAND (EXPN)command syntaxes are changed to:
 
-       "VRFY" SP uAtom [SP "UTF8REPLY"] CRLF;
-              ;uAtom is defined in section 2.3 of this document
+       "VRFY" SP (uLocal-part / uMailbox) [SP "UTF8REPLY"] CRLF;
+              ;uLocal-part and uMailbox is defined in section 2.3 of this document
 
-       "EXPN" SP uAtom [SP "UTF8REPLY"] CRLF;
-              ;uAtom is defined in section 2.3 of this document
+       "EXPN" SP (uLocal-part / uMailbox) [SP "UTF8REPLY"] CRLF;
+              ;uLocal-part and uMailbox is defined in section 2.3 of this document
 
    This parameter "UTF8REPLY" does not have value.  If SMTP reply
    requires UTF-8, but SMTP client does not use "UTF8REPLY" parameter in
-   the VERIFY (VRFY) and EXPAND (EXPN) commands, the response code "252"
+   the VERIFY (VRFY) and EXPAND (EXPN) commands, the response code 252
    is used, defined in [RFC2821], meaning "Cannot VRFY user, but will
-   accept the message and attempt the delivery".  If enhanced mail
-   system status code [RFC3463] is used, the response code should be
-   "5.6.y" or "2.6.y" [SMTP-codes], meaning that "The UTF-8 reply
-   required, but the UTF8REPLY parameter not used.". [[anchor13: REMOVE
-   THIS: IANA please assign the proper error codes for "5.6.y" and
-   "2.6.y".]]  "UTF8REPLY" on the VERIFY (VRFY) or EXPAND (EXPN)
+   accept the message and attempt the delivery". Also response code 550
+   may be used, meaning "Requested action not taken: mailbox unavailable". 
+   If enhanced mail system status code [RFC3463] is used, response codes 
+   given on below is used. "UTF8REPLY" on the VERIFY (VRFY) or EXPAND (EXPN)
    commands enables UTF-8 for that command only.
 
    The uAtom of the VRFY and EXPN commands is a user name or a user name
    and a domain (see below).  If a normal (i.e., 250) response is
    returned, the response MAY include the full name of the user and MUST
    include the mailbox of the user.  It MUST be in either of the
@@ -658,12 +664,20 @@
                 ; uMailbox is defined in section 2.3 of this document
                 ; User Name allows the non-ASCII character.
 
          uMailbox
                 ; uMailbox is defined in section 2.3 of this document
 
+
+   If SMTP reply requires UTF-8, but UTF-8 is not allowed on reply,
+   and enhanced mail system status code [RFC3463] is used,
+   the response code should be  "5.6.y" or "2.6.y" [SMTP-codes],
+   meaning that "The UTF-8 reply required, but not allowed.".
+   [[anchor13: REMOVE THIS: IANA please assign the proper error codes
+   for "5.6.y" and "2.6.y".]]
+
    If the SMTP Client lack of the UTF8SMTP support receives the UTF-8
    message on reply, it may crash.  UTF-8 messages on reply are only
    allowed in the commands under the situations described above.  Under
 
 
 

---------------------------------------------------------------------------

Discussion:

1) 

SMTP client needed to be required to accept UTF-8 also on RCPT response.

2)

251  response with UTF-8 mailbox can be replaced with 250 response. 
250 response does not include new address.

Instead of

        RCPT TO:<support at example.com>
        251 2.1.5 New address is <kÃyttÃjÃtuki@@example.com>, will forward

use

        RCPT TO:<support at example.com>
        250 2.6.y Address is changed, will forward


Of course 251 can not replaced with 550 because that recipient is accepted.
Therefore 250 is correct response code.

3)

--- start quote --
This parameter "UTF8REPLY" does not have value. If SMTP reply
requires UTF-8, but SMTP client does not use "UTF8REPLY" parameter in
the VERIFY (VRFY) and EXPAND (EXPN) commands, the response code "252"
is used, defined in [RFC2821], meaning "Cannot VRFY user, but will
accept the message and attempt the delivery". If enhanced mail
system status code [RFC3463] is used, the response code should be
"5.6.y" or "2.6.y" [SMTP-codes], meaning that "The UTF-8 reply
required, but the UTF8REPLY parameter not used.".
--- end quote ---

Here is problem that that talks only response code "252", but
enchanced response codes talk both "5.6.y" and "2.6.y".

These "5.6.y" and "2.6.y" are fine -- these should NOT removed.

Problem is that these enchanced response codes now apply only
to VERIFY and EXPAND. My original text these apply also to
RCPT command.

On that change effectively
   ``If enhanced mail
     system status code [RFC3463] is used, the response code should be
     "5.6.y" or "2.6.y" [SMTP-codes], meaning that "The UTF-8 reply
     required, but the UTF8REPLY parameter not used."??
is moved just to new chapter so that it applies to RCPT
-command also. menaing text is also of course change, because 
RCPT command here did not taken UTF8REPLY paramater.

4)

Limiting VRFY and EXPN to uAtom is very restrictive.

RFC 2821 quote: ------------------------------


   "User name" is a fuzzy term and has been used deliberately.  An
   implementation of the VRFY or EXPN commands MUST include at least
   recognition of local mailboxes as "user names".  However, since
   current Internet practice often results in a single host handling
   mail for multiple domains, hosts, especially hosts that provide this
   functionality, SHOULD accept the "local-part at domain" form as a "user
   name"; hosts MAY also choose to recognize other strings as "user
   names".
---- end RFC 2821 quote -------------------------------


uAtom do not accept "@domain" which is "SHOULD" on RFC 2821.

With suggested syntax it roughly matches with RFC 2821 text.


Yes, actual syntax on RFC 2821 is somewhat conflict with
this:
 
RFC 2821 quote: ------------------------------
4.1.1.6 VERIFY (VRFY)

   This command asks the receiver to confirm that the argument
   identifies a user or mailbox.  If it is a user name, information is
   returned as specified in section 3.5.

   This command has no effect on the reverse-path buffer, the forward-
   path buffer, or the mail data buffer.

   Syntax:
      "VRFY" SP String CRLF

4.1.1.7 EXPAND (EXPN)

   This command asks the receiver to confirm that the argument
   identifies a mailing list, and if so, to return the membership of
   that list.  If the command is successful, a reply is returned
   containing information as described in section 3.5.  This reply will
   have multiple lines except in the trivial case of a one-member list.

   This command has no effect on the reverse-path buffer, the forward-
   path buffer, or the mail data buffer and may be issued at any time.

   Syntax:
      "EXPN" SP String CRLF

---- end RFC 2821 quote -------------------------------

Where String seems to be

         String = Atom / Quoted-string



( And anyway uAtom do not cover Quoted-string which is allowed on 
  String ).

Seems that  RFC 2821 is mess on here also :-(


/ Kari Hurtta



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