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Re: New Sieve extension "refuse" proposal - draft-elvey-refuse-sieve-01h

2004-02-22 15:29:43

On 2/20/2004 9:41 AM, ned(_dot_)freed(_at_)mrochek(_dot_)com sent forth 
electrons to convey:

> The main problem with the idea of relaxing the rules for reject to
> allow it to
> generate DSNs or a 5xy error when running on an MTA is that a script will
> behave in a fairly different way depending on whether you run it on an
> MUA or a
> MTA. I really don't like this. And if you use a require tag to mean
> "change the
> semantics of reject to refuse" and make it so the tag only works  on
> MTAs,
> you're back to having to change the scripts when you move them around.
> Its just
> generally cleaner to have two different actions here and have one of
> them be
> MTA-only.

It's unavoidable for behavior to differ between an MUA and an MTA, if
there is support for a "refuse" action.

This presupposes that refuse is supportable on an MUA. I don't think it is or
should be.

What solution do you suggest to avoid a script either behaving
differently or having to be different ?

I suggest that if you want a portable script you use reject and live with
its limitations. If, on the other hand, you are willing to live with an
MTA-only script, you have the option of using refuse.

You're almost saying you want both, but isn't that an impossibility?

No. See above.

A require tag that means "change the semantics of reject to refuse"
seems to have the fewest drawbacks.

I disagree. There's only a small incremental cost of switching rejects to
refuses throughout compared to the cost of switching just the require clause.
And you lose the ability to have both behaviors, which is something a large,
composite script might want.

I think it's impossible for a script that uses a "refuse" action to be
and behave the same on an MUA and an MTA.

It is impossible to implement refuse on an MUA, period.

This is still a problem with Cyrus' proposal: what would happen if
"refuse smtp5" was attempted in a script on a MUA?  It still would
require a change on a mail agent that couldn't do SMTP time refuses.

Here's an idea!
Perhaps "refuse" should have an "Am I an MTA capable of refusing?" test
or constant?
Then users wouldn't have to add/remove the <require "refuse"> string
when moving a script between MUA and MTA.

A major wart like this is entirely unwarranted IMO.


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