E-mail address forced to lower case in user ID?!?

[Nathan Kennedy]

Rich Wales wrote:
> 
> I noted today that the e-mail address portion of a user ID is always
> forced to lower case.  (g10/keygen.c, function ask_user_id, line 611.)
> 
> If this is going to be done, it should really only be done for the
> domain name (the part to the right of the "@" sign).  The user name
> (left-hand side) in an e-mail address is explicitly allowed to be
> case-sensitive in the Internet e-mail standard (RFC822, sec. 3.4.7).
> 
> As far as I'm aware, very few (if any) modern e-mail systems actually
> care about upper vs. lower case in their own local user names. 

Last I checked, login names are CaSe sEnsiTive in *NIX, just like anything
else in UNIX or C.  I've never done it (I always use lower case for login
names, and that is accepted practice with UNIX), but you could have one
user named Joe and another named joe.  Now-- I telnetted and tried it, and
it seems that some (all recent?) sendmails will kludge the capitalization,
but-- a) I've seen many systems that don't do this. b) There is the case
where alternate capitalizations == different users.

> But
> since the standard permits case sensitivity, it seems to me inappro-
> priate to force the left-hand side of the address to lower case when
> constructing a key's user ID.

Right.  The sendmail kludge is to keep the deluge of complaints from
puzzled Windows users to an minimum (I've had to explain this to people
over and over.  Even if it's a kludge, I'm personally thankful for it). 
Usernames *are* case-sensitive in *NIX and friends, and last I checked most
MTA's run *NIX and friends.  Not only is it a standard (And a Good Thing),
I've actually seen more than one address that used mixed case that bounced
when the case was alterred.

Nate