Re: I-D Action: draft-ietf-sieve-imap-sieve-08.txt

On 9/10/2012 11:16 PM, [email protected] wrote:
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>   This draft is a work item of the Sieve Mail Filtering Language Working Group of the IETF.
>
> 	Title           : Support for Internet Message Access Protocol (IMAP) Events in Sieve
> 	Author(s)       : Barry Leiba
> 	Filename        : draft-ietf-sieve-imap-sieve-08.txt
> 	Pages           : 23
> 	Date            : 2012-09-10
>
> Abstract:
>     Sieve defines an email filtering language that can, in principle,
>     plug into any point in the processing of an email message.  As
>     defined in the base specification, it plugs into mail delivery.  This
>     document defines how Sieve can plug into points in the IMAP protocol
>     where messages are created or changed, adding the option of user-
>     defined or installation-defined filtering (or, with Sieve extensions,
>     features such as notifications).  Because this requires future Sieve
>     extensions to specify their interactions with this one, this document
>     updates the base Sieve specification, RFC 5228.

There is no changelog in the document, so I wondered what changed and 
therefore I read it again. Rather than finding out what had changed, I 
noticed a few other things:

#1) The final paragraph of Section 2.1 lists a few IMAP and Sieve 
capabilities for which support is required: IMAP "METADATA" and Sieve 
"environment". I would expect this Section to list all such 
dependencies, but apparently it does not. Section 3.8 adds the Sieve 
imap4flags extension as a requirement. Yet, section 4.5 suggests that it 
is optional again. So what is it?

#2) Section 2.2.2 suggests that there is a MULTIAPPEND command for IMAP. 
There is no such thing: it is an IMAP capability that extends APPEND to 
accept multiple messages at once. I would merge this with the previous 
section:

--
2.2.1. The IMAP APPEND Command

    A message may be added to a mailbox through the IMAP APPEND command.
    In a server that advertises "imapsieve", new messages added in this
    way MUST trigger the execution of a Sieve script, subject to the
    settings defined through Metadata (see Section 2.3.1).

    If the IMAP server supports the IMAP MultiAppend extension [RFC3502],
    multiple messages may be added to a mailbox through a single APPEND
    command.  In a server that advertises "imapsieve", new messages added
    in this way MUST each individually trigger the execution of a Sieve 
script.
--

This also stresses the fact that each individual message triggers the 
Sieve script. At other places in the document MULTIAPPEND is listed as a 
separate command, but there it would suffice to just remove it.


I also gave the issue of useless script triggers, i.e. events that are 
never of interest for the script involved, some more thought. For 
example, I would hate to have my Sieve script executed for each message 
that I read (added \Seen flag) while it doesn't do anything useful with 
that event. Wouldn't it be useful to have a `/shared/imapsieve/cause' 
Metadata item that indicates which causes (the items from Section 7.3.1 
in a space-separated list) should trigger the Sieve script? More 
detailed control could be used to select specific flags that are 
relevant (e.g. in a '/share/imapsieve/changedflags' Metatada item).

Regards,

Stephan.
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