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Re: draft-elvey-refuse-sieve-02.txt; http://wiki.fastmail.fm/wiki/index.php/SieveExtensionsSupportMatrix




Hi Matthew,


--On Tuesday, August 10, 2004 11:36 AM -0700 Matthew Elvey <matthew@xxxxxxxxx> wrote:

There was some discussion at the lunch BOF last week about the utility
of refuse.

Cool; wish I coulda been there/participated. Anyone take minutes? (edit: I just heard that Alexey has notes he may share.)

The Jabber log is here:


<http://www.xmpp.org/ietf-logs/sieve@xxxxxxxxxxxxx/2004-08-04.txt>

I will also attempt to write up a brief summary and post to the list in the next day or so.

There was general consensus among the participants that it would be
better to extend reject to allow for SMTP refusal and DSN generation
rather than add a new command. Personally I prefer that approach - but
the issue needs more discussion on the list.

We've probably been over this before, but can you explain in detail
why you think a new command is better than extending the behaviour of
reject?

So the idea is just a syntax change, yes?

A syntax change and also a relaxation of the requirement that 'reject' must generate an MDN. i.e. if 'reject' occurs in an implementation that runs SIEVE during SMTP then that implementation is allowed to do either an SMTP error code, DSN or MDN as it feels appropriate. The 'reject' text specified by the user would be used for DSN or MDN text, and we would add a new optional parameter for the SMTP error code and descriptive error text.


What's the gist of the argument for the change? I can't think of any
strong arguments against the change; here are some less strong arguments:

1)A normal extension (the current 'refuse') is a cleaner implementation
in the sense that it's a standard extension - something that's well
understood, instead of something that makes the base Sieve RFC 'wrong' by
changing it.

My argument against a new command is that it makes scripts less portable. By relaxing the restriction on reject the same script can run efficiently on an implementation that runs at SMTP time and one that runs at final delivery/LMTP time. It will also make switching between such implementations easier as scripts will not have to be changed to gain the benefits of SMTP time rejection.


The question is whether there is ever a case where you would care what type of reject behaviour is carried out: SMTP error, DSN or MDN. If there is a requirement to allow users to explicitly state the type of error that can easily be done as a parameter.

2)It's already written and debugged.

True, but I don't think switching to 'relaxed' reject would be a significant change. I suspect the integration with SMTP is the biggest issue.


Arguments for the change:
1)A change won't break anything, according to the URL below.

Have we done something like this (e.g. modify an action to accept a
special parameter flag) before?

Yes - the copy extension adds a :copy parameter to fileinto and redirect. imapflags also extends fileinto and also keep.



-- Cyrus Daboo