Even though RFC5321 2.4 explains that local-parts are to be case-sensitive,
this does not seem to be how EMail is used today. Thus, instead of reverting
user-emails back to being case sensitive, let’s make aliases case-insensitive
too. Not only more consistent, this also allows users to enjoy receiving EMails
from large airlines or car-rental agencies onto their already existing aliases.
For the rare case of case sensitive aliases existing, let’s query for the
forced-lowercase alias only in the event that the preserved-case one isn’t
found …
closes#867
