Re: [EAI] Discussion of draft-ietf-eai-mailinglist-01.txt

["Charles Lindsey" <chl at clerew.man.ac.uk>]

On Sun, 18 Mar 2007 10:11:31 -0000, Randall Gellens <randy at qualcomm.com>  
wrote:

> At 7:56 PM +0000 3/13/07, Charles Lindsey wrote:

> >  The question is how to bring this about? Martin has declared  
> > willingness to bring it into his new mailto draft at some stage (and  
> > now we at least have an agreed notation for him to use). But I don't  
> > think it would be a good idea to invent our own mechanism, with its own  
> > downgrade, for use in the interim. Better to forego the possibility of  
> > alt-addresses for the moment, with a NOTE to explain that an extended  
> > mailto syntax is expected to be defined in the near future. But, in  
> > fact, there is another way:
> >
> >  The alternative is to use two URIs or IRIs in those headers which need  
> > it. RFC 2369 is not particularly well written, but if you examine it  
> > closely you will see that comma-separated lists of URLs are allowed. So  
> > one could have, for example:
> >
> >     List-Post: <utf8-submission at utf8>, <ascii-submission at ascii>
> >
> >  and RFC 2369 already tells you to examine them from left-to-right and  
> > to use the first which you have the capability to use.
>
> I'm concerned that many existing implementations of List-* headers  
> wouldn't work in this case.  (Either they wouldn't handle multiple  
> addresses, or if they did, they wouldn't handle UTF8 addresses.)

Well RFC 2369 declares that such comma-separated lists are part of the  
standard, so any implementation that barfs on them is broken.

But, first of all, can we look at how these headers are actually used? To  
a large extent, surely, they are for human use. A human wants to  
unsubscribe from the list, so he asks his browser to show all the headers,  
finds the one that says List-Unsubscribe, and clicks on what he sees there  
(which will presumably be a mailto:).

So which of these headers is likely to be looked at an acted upon by some  
software that need to understand them? What is current practice here?

The obvious candidate is the List-Post header, which might be examined by  
some MUA in response to pressing a "Followup" button (in fact, I wish MUAs  
would provide such a button instead of forcing you to use Reply or  
Reply-to-All, neither of which do what you actually want). Such a facility  
would certainly expect to see a mailto: and to try to mail the followup to  
it, and if it found a utf8 address there might get upset (a  
UTF8SMTP-capable MUA, of course, might look to see if there was a second  
ascii address and use that if its MSA demanded downgrading).

But I doubt any existing agent is actually going to barf if is sees more  
than one address. More likely, it will try the first one it sees, and  
never look any further.

As to what happens when a non-UTF8SMTP agent sees a utf8 address, then  
that is a fair question. Note that it could easily see such an address  
even in a dongraded message, since any IRI would simply have been  
downgraded to a URI, and the utf8 address wold still be there, but %hex  
encoded.

Again, if a human sees that, and also sees a second ASCII address, he will  
surely click on the right one. An automated system is going to be confused  
whatever we put in there, unless we specify a downgrade mechansim that  
specifically looks at the mailto:s in the List-* headers and removes any  
utf8 addresses and just leaves the ascii ones.
> It might be safer to have new List-* header fields for EAI addresses.
>
> So, an EAI list might include two sets of each List-* header, one for  
> ASCII address using the existing List-* header names, and one for EAI  
> addresses, using the new List8-* names.

That seems like too much departure from the present usage. We should avoid  
that unless we absolutely cannot see any other way.

But, first, we really do need to know what current software actually does  
with those headers, other than to display them.

--
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131 ;                      
   Web: http://www.cs.man.ac.uk/~chl
Email: chl at clerew.man.ac.uk      Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K.
PGP: 2C15F1A9      Fingerprint: 73 6D C2 51 93 A0 01 E7 65 E8 64 7E 14 A4 AB A5

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