List Flag: match-domain

Makes a more complete attempt to determine if an incoming message belongs
to a current subscriber by comparing domain names rather than full hostnames.
In other words, this flag allows someone with accounts on multiple machines
from one domain to subscribe only once.

For example, if dot@wakko.animaniacs.net were an owner of a list, but one
day was using another account at the same site called dot@yakko.animaniacs.net,
the user's owner access would not be available under normal circumstances,
because "dot@wakko.animaniacs.net" and "dot@yakko.animaniacs.net" aren't
identical.  If "match-domain" is set, the hostname portion is stripped,
so listmanager instead compares "dot@*.animaniacs.net" to
"dot@yakko.animaniacs.net" which matches, and access is granted.

NOTE: Turning this flag on causes an n^2 search algorithm to be applied when
adding a lot of users with "add" or "import" commands.  This will be optimized
in a future release.  If you are importing your list from another mailing
list system and want to use this flag, turn the flag off before the import
and turn it on again afterwards.