Why do "unix"-people have a problem? (1)
 
RFC822 tells that addresses should be case insensitive.
In real life "names" are also to a certain extent case insensitive.
If you look a bit closer to unix systems you will find that
unix has the concept of a "login", i.e. the equivalent of a
"userid" in IBM and other systems. In unix you also have a
"username", therefore it always irritates me that people
have "login"="username". Well, but why not. This is the old story
between  ERIC@FRECP11 and GRZ027@DBNGMD21 . Now Unix systems
allow mixed case in "login"s. On the other hand Unix thinks
that a terminal does not support lowercase characterswhen
a "login" is entered in uppercase only.
 
Conclusion:
 
Eric can decide to translate all addresses to uppercase and use
this for routing decisions and as input for MAILER.
MAILER is also free to do this in BSMTP messages to other mailers.
 
Unix systems which have a problem with that should correct their
system and ask to support this kind of misbehaviour.
The german UUCP-EARN gateway uses the following
heuristics when it delivers messages to UUCP.
When a message arrives where all characters are uppercase, this
is translated to lowercase. Mixed character addresses are
left as is (I'm not quite sure if the latter is still true).
 
Peter
 
 
(1) UNix is a registered trademark of Bell Labaroratories