user part of domain names case-folded for bounces

Problem:

As a non-subscriber, if you email a subscription-only
list from XYZ@foo.com, the bounce that it is either in
a queue or rejected comes back to xyz@foo.com.

Comments:

I am not familiar with the Mailman code. I am not sure
if there is a simple fix. At really first glace
Utils.py has some probably incorrect code in the
ParseEmail function. I am not sure if this is the
cause, and if so, if it has any side-effects by
changing it. I know Mailman internally stores the user
part as lower case, but for mail delivery purposes it
should retain the case.

The function (in 2.1.6b4) I am guessing should probably
look more like this:

def ParseEmail(email):
user = None
domain = None
at_sign = email.find('@')
if at_sign < 1:
return email, None
user = email[:at_sign]
rest = email[at_sign+1:].lower()
domain = rest.split('.')
return user, domain