Re: UUCP, etc., and SMTP/822/MIME mail (was: Re: I-D ACTION:draft-hoffman-utf8headers-00.txt)

On Fri, 02 Jan 2004 12:03:50 -0500, Martin Duerst <[email protected]> wrote:


> - Is a message tagged with Charles' header allowed to contain RFC 2047 
> stuff?
>    (I would propose we say: MAY contain RFC 2047-encoded stuff)

Yes, I would think so.

> - Is a message passed over SMTP with UTF-8-HEADERS allowed to contain
>    RFC 2047 stuff?

Yes, I don't see why not. In the fullness of time, one hopes that the use 
of RFC 2047 will gradually disappear, but it is for the marketplace to 
determine when.

> The way I understand SMTP extensions (experts on this
>    list, please correct me if I'm wrong), this is a somewhat moot 
> question,
>    because it's the server that says what extensions it supports; the 
> client
>    doesn't say which extensions it uses (unless through the use of
>    parameters in commands, but there are none for UTF-8-HEADERS).
>    So my understanding is that RFC 2047-encoded headers are not 
> disallowed.

But here I have a problem. RFC 2821 seems written on the assumption that 
the client is just the last server in the chain, so of course it can 
announce whether it supports UTF-8-HEADERS or not.

But, in practice, what happens is that the last SMTP server in the chain 
hands of to a "local delivery agent", which may turn out to be a POP3 
store or an IMAP store of a huge MBOX file or whatever else. So in 
practice the local delivery agent needs to be able to say the equivalent 
of "I do/do not do UTF-8-HEADERS" and then the server knows whether to 
downgrade/bounce/etc. Alternatively, the local delivery agent is smart 
enough to downgrade/bounce itself (that sort of thing could be configured 
into procmail, for example).

However, there don't seem to be any standards covering this area (you just 
have to learn how to hack sendmail.cf or its equivalents), so there is 
nowhere for us to specify such expectations.

> - Does 'upgrade' include conversion from RFC 2047-encoded headers to
>    raw UTF-8 (even if the RFC 2047 encoding doesn't use UTF-8)?

My view is that upgrading is best left to the latest possible point in the 
chain. The less that intermediate servers do to messages, the better 
(because they usually do more harm than good). So leave it to the IMAP 
store, or the MUA it at all possible.

The one possible exception is where it was clear that the header in 
question has previously been downgraded in accordance with this same 
standard.

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
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