Re: Filtering Header Draft Discussion

On Oct 16 2004, J.J.Bailey wrote:
> 
> Does anyone have a feel for how much effort is being put into client-
> side filtering?  I'm curious to know what's driving the standard and
> who needs what where.

Well this group is somewhat research oriented, so we might not end up
with an actual standard;-)

If you read the past discussion on the list, there's a wide variety of
headers used in the wild, andthe list is growing. We did a quick
survey on one of the threads on this list, but if anything it showed
lots of variation.

I believe the main interest for the filtering standard is to identify
whether we can formalise a common extensible format which would 

1) allow machines to robustly read header contents without needing
separate custom parsers for each header.

2) identify and solve(?) issues such as authentication, overwriting,
modification, removal, coherence which are otherwise decided by each filter on an
ad-hoc basis.
 
3) be simple and easy enough for all interested parties to implement.

For example, the key/value pair format helps with 1).

In the case of 2), consider the following header:

X-Filtered-by: Plusnet (hmail v1.01)

This is practically useless. As a third party, you don't know which other
headers are related to this one (ie belong to Plusnet), you also don't
know where in the mail transport this header was added. Finally, it doesn't
even actually say anything of value. It's really just a waste for anyone except
the Plusnet mail filtering system, which presumably can use it for something.
Even for Plusnet, can the system be sure it added the header itself, or did a spammer
forge the header?

Finally, 3) goes without saying.
I'm sure there are other interests driving the standard, but those are some of them. 

-- 
Laird Breyer.