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Comments on draft-melnikov-sieve-external-lists-02.txt

2009-07-19 14:51:31

Hi Ned,
I've changed the subject and moving my reply to the Sieve mailing list, where I think it belongs.

Ned Freed wrote:

There is also a Sieve extension for making use of whitelists/blacklists
during mail delivery. See draft-melnikov-sieve-external-lists-02.txt.
It can work with CARDDAV, LDAP and other things.

Interestingly, this extension in its current form is not compatible with
at least one of the proposals that was made here. The issue is one I've
raised before - the fact that :list is separate argument and not a match type.

Where there is clearly some utility in being able to say stuff along the
lines of:

   header :contains :list "subject" "tag:dirty-word-list"

The problem is that in order for this to work the list has to be enumerable.

This wasn't the intent. I was certainly aware of the need not to retrieve the whole membership list.
But you are saying that my syntax wouldn't work in this case.

Not all lists are enumerable, and even some that are are so large even though oyu can enumerate them in theory you can't afford to do so in practice.

One use case where this matters is when the list is a set of hashed values. The way you find if something is "on the list" is to hash it and see if that value appears. And even if the input string is short enough that you can enumerate
all the unique substrings, how about :matches and :regex? Good luck with

Hashed lists have in fact been proposed in the present discussion as a means of avoiding giving your address whitelist to the mail server. I happen not to think this is a useful thing to do for a variety of reasons, mostly having to
do with address canonicalization (or lack thereof), but there are other
use cases where hashed lists make more sense.

So, although it reduces functionality, I believe :list should be a match type and the underlying comparison type that's done should be a property of the list

Hmm. You are probably right, :list as a modifier is a bit of a hack.
How would the new match type work with tests other than header/address/envelope?