Subject: Re: [EAI] Strip 8th bit (was: Fwd: Re: Minutes from Prague)

From: "Charles Lindsey" <[email-masked]>
Date: Tue, 01 May 2007 11:44:27 +0100

On Mon, 30 Apr 2007 19:35:27 +0100, John C Klensin <[email-masked]> wrote:

> --On Monday, 30 April, 2007 11:58 +0100 Charles Lindsey
> <[email-masked]> wrote:

>> Clearly, bouncing the message as FUBAR is always the safe
>> option.
>>
>> But I think it better, if you are determined to try to
>> continue with delivery, just to send the 8bits regardless
>> rather than to strip the MSB (this is what sendmail does
>> AFAICT).
>
> But this is exactly the "just-send-8" option that was rejected
> during the original MIME work, rejected again when MIME advanced
> to Draft, and rejected again by DRUMS (and maybe a few other
> times).  Even if you were right, it would be too late.

You misunderstand. I am not trying to make such things legal.

All I am trying to say is that, if you have something that is illegal, and  
are determined to send it on regardless (as opposed to bouncing it), then  
it is better to send it on in an illegal form rather than to force it to  
be legal by making arbitrary changes, such as dropping MSBs. It is a  
matter of choosing the lesser of two evils.
>
>> ....
>> And it is strictly of-topic for this group, ...
>
> So, why are you bringing it up here?

I was merely responding to a remark by Frank, who was in turn responding  
to a remark by Harald.

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131                       
   Web: http://www.cs.man.ac.uk/~chl
Email: [email-masked]      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

_______________________________________________
IMA mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/ima

---

From: Frank Ellermann <[email-masked]>
Date: Tue, 01 May 2007 21:15:37 +0200

> If minimal MIME conformance requires to support message/partial
> and/or message/external-body add the missing steps.

That was hogwash, message/partial is guaranteed to be 7bit, and
adding the missing steps to handle it in an "8to7" algorithm is
trivial.  

And a message/external-body (the lines defining it, encapsulated 
header + phantom body) is also guaranteed to be US ASCII, that's
also trivial.

IMO we should now decide that any attempt to allow UTF-8 in MIME
part headers or generally Content-* header fields is doomed.  If
you (= EAI folks) want to try it anyway please say so, because
I don't like to waste more time with it.  

Frank

---

From: Chris Newman <[email-masked]>
Date: Tue, 01 May 2007 23:37:18 -0700

The WG would need a very good reason not to support native UTF-8 in the 
Content-Disposition filename parameter.  There is a clear need for that if 
we're doing "UTF-8 clean" i18n headers, and the standards track encoding 
mechanism (2231) has had more deployment/interop problems than general 2047 
header encoding.

                - Chris

---

From: "Charles Lindsey" <[email-masked]>
Date: Wed, 02 May 2007 12:28:58 +0100

> I don't like to waste more time with it.

Why should it be "doomed"?

We know exactly how to downgrade all known Content-* headers, and the  
result of downgrading should be comprehensible to existing agents,  
assuming they understand RFC 2047 and RFC 2231 (and if they don't they  
will just display the stuff still encoded, or in the case of <paramater>s  
ignore them, as presumably happens already). There is never any need to  
construct a Downgraded header,

And we also know how to deal with such headers when they occur in MIME  
part headers - it is simply a matter of extending the code in current MTAs  
that already handles the 8BITMIME downgrading, so that it looks at and  
downgrades those headers before it looks and and encodes the bodies that  
follow them.

---

From: Tony Finch <[email-masked]>
Date: Sat, 12 May 2007 09:41:59 +0100

On Thu, 26 Apr 2007, Harald Tveit Alvestrand wrote:

> I believe that both PP and Exim defaulted to "strip the 8th bit" for quite a
> while. I'm not sure what current mailers default to.

Sorry for the delayed reply. AFAIK Exim has always been 8-bit clean. Its
oddity in this area is that it can be configured to offer 8BITMIME but it
does not implement 8bit -> 7bit downgrades.

Tony.
-- 
f.a.n.finch  <[email-masked]>  http://dotat.at/
VIKING NORTH UTSIRE SOUTH UTSIRE: EAST BACKING NORTHWEST 4 OR 5, OCCASIONALLY
6. MODERATE OR ROUGH. SHOWERS. GOOD.

---

From: John C Klensin <[email-masked]>
Date: Sat, 12 May 2007 06:38:34 -0400

--On Saturday, 12 May, 2007 09:41 +0100 Tony Finch
<[email-masked]> wrote:

>> I believe that both PP and Exim defaulted to "strip the 8th
>> bit" for quite a while. I'm not sure what current mailers
>> default to.
> 
> Sorry for the delayed reply. AFAIK Exim has always been 8-bit
> clean. Its oddity in this area is that it can be configured to
> offer 8BITMIME but it does not implement 8bit -> 7bit
> downgrades.

Which, of course, is completely permitted by the standard unless
it sends 8-bit to hosts that do not advertise 8BITMIME.

     john