Re: [art] [Last-Call] Artart last call review of draft-ietf-extra-imap-messagelimit-08

[Alexey Melnikov <[e-mail]>]

Hi Barry,

To close the loop:

On 13/03/2024 19:42, Barry Leiba via Datatracker wrote:
> Reviewer: Barry Leiba
> Review result: Ready with Issues
>
> General comment:  It seems very odd for this to apply to EXPUNGE.  First, the
> overhead in expunging is low.  Second, the client has no control over the
> number of messages that will be expunged, as it just has to do with which
> messages happen to have the /Deleted flag set on the server, and having a limit
> on UID EXPUNGE and not on EXPUNGE would be strange and hard to justify.
We have briefly discussed this in the EXTRA WG meeting in Brisbane and 
agreed that if there are no unexpected side effects of this, then I will 
make EXPUNGE and UID EXPUNGE behave in the same way, i.e. with no limit 
applying to them.
> — Section 3.1 —
>
>     If a server implementation doesn't allow more than <N> messages to be
>     operated on by a single COPY/UID COPY command, it MUST fail the
>     command by returning a tagged NO response with the MESSAGELIMIT
>     response code defined below.
>
> I think this needs to be clearer that the entire command is failed and that
> *no* messages are copied.  It should not just rely on the example later in the
> section to convey that.
I will clarify this.
>     When IMAP MULTIAPPEND [RFC3502] extension is also supported by the
>     server, the message limit also applies to the APPEND command.
>
> Is that really all you want to say about using this with APPEND?  I think that
> leaves it underspecified.  How is a partial result handled?  Tagged OK with
> partial result?  Tagged NO with complete failure of the command?  And how about
> including an example?
MULTIAPPEND APPEND is actually atomic (as per the MULTIAPPEND spec), 
i.e. it can't partially fail. But I will spell this out in more details.
> — Section 3.5 —
>
> You are now making it permissible for servers to break compatibility with
> clients that don’t support this new extension; that seems troubling.  I
> understand that possibly servers are already doing that, but it seems bad to
> define an extension that says it’s OK… basically, if you implement this
> extension, you are abandoning older clients.
>
> It would seem better to have the section talk about the i portance of
> maintaining compatibility with clients that don’t support this extension, and
> raise the possibility of abandoning compatibility only if it’s absolutely
> necessary.
>
> For example, one might suggest tolerance of the situation to some extent,
> allowing older clients to exceed the message limit to a point in order to stay
> compatible, but recognizing the need to stop when it’s excessive.  Maybe if the
> limit is 1000 you still accept up to 5000 from a non-compliant client before
> you give up, or something like that.
>
> This is especially true for flag searches, for which much greater tolerance is
> probably acceptable.  Maybe true for STORE as well.

In Brisbane we agreed that two of us will wordsmith some text allowing 
soft limit.

Best Regards,

Alexey