Re: Question: Fullwidth double-quote and fullwidth backslash

--On Thursday, 03 July, 2003 21:02 +0000 "Adam M. Costello" 
<[email protected]> wrote:

>...
> Do ordinary users deal with quoting in local parts?  The RFC
> 2821/2822 local part syntaxes allow metacharacters
> (double-quotes and backslashes), but do local parts seen by
> regular users ever contain those characters?  I can't remember
> ever encountering a real local part that needed a double-quote
> or backslash.

Adam, one instance of this used to be fairly common, and I still 
see it with some (although small) frequency.  That involves 
receiving SMTP servers that interface to local systems that

	(i) Use the local user name, or workstation name, as an
	email local part
	
	(ii) Use spaces in the local user name

e.g., you would end up with a local user name, or workstation 
name, of "Adam Costello" and an email local-part of
    "Adam Costello"   or
    Adam\ Costello

Note that these systems may not be gateways, since the interface 
is to a local mailstore on the receiving system rather than to a 
different mail transport environment.   The MUAs on those 
systems typically handle these addresses unquoted, quoting them 
only when moving into SMTP environments, but a sender from 
another system usually has to deal with the quotes.

These types of local address formats are becoming less common. 
But that is less, IMO, a direct consequence of SMTP becoming 
ubiquitous than the result of years of experience that such 
addresses, on the Internet, become a pain in sensitive parts of 
the anatomy, cause excessive support costs, etc.  Counting on 
none of them being out there would represent very bad protocol 
design.

That said, if i18n addresses can be distinguished from 
historical ones in some 100% reliable way, I see no reason to 
avoid making rules about them that provide good functionality 
and place conversion responsibility onto the gateways and/or 
receiving systems with odd ideas about addresses.  Put 
differently, giving those systems a choice between oddities with 
ASCII addresses and i18n addresses seems to me to be a rational 
tradeoff.

     john