[PATCH][CVS IMAPd 2.1] lmtp_downcase_rcpt implementation (2)

[John Alton Tamplin]

Lawrence Greenfield wrote:

>Well, "message delivery" and "mailbox names" are tightly
>intertwined. How should I know that "leg+detail" should be delivered
>to "user.leg.Detail"?
>  
>
There is no historical usage that says imap folder names within a 
mailbox aren't case sensitive, so I would say leg+Detail should be 
delivered to user.leg.Detail and leg+detail should bounce (or actually 
get dropped into INBOX). The issue is that users have treated mail 
addresses as case insensitive and other implementations have enforced that.

>You also need to prevent two mailboxes from being created with the
>same name (except for case).
>
If we are only talking about smashing the case on user names and 
therefore mailboxes, couldn't that be handled both for delivery and 
other uses in mboxname*_tointernal?

>There's the i18n problem: case mapping isn't trivial across lots of
>languages.
>  
>
True.  Since mail addresses are defined in US-ASCII, where is the 
mapping from RFC2047 into the actual characters done?  It seems the case 
mapping should be done there, at the point you know the character set. 
 If, as in most cases, it is US-ASCII or a Latin1 character set, it is 
easy to implement.  That will get the majority of the need with little 
effort.  For those other character sets, it isn't clear there is as much 
of a need since they don't have historical implementations that smashed 
case in the user part of the email address to deal with.

>Finally, we need to deal with people toggling this option on and
>off. What happens if user.leg.foo and user.leg.Foo both exist, and
>then the administrator turns on case-insensitivity?
>  
>
Since what I am proposing only affects user names, that example wouldn't 
be a problem.  If user.foo and user.Foo exist and the option is turned 
on, then user.Foo won't be able to receive any mail.  I don't think 
Cyrus should protect sysadmins from that any more than it should protect 
against them deleting a mailbox they shouldn't.

-- 
John A. Tamplin                               Unix System Administrator
Emory University, School of Public Health     +1 404/727-9931