This decision is left to the MX (as for 'fripostIsStatusActive'), which
will set the envelope recipient accordingly.

So our suffix is now a mere 'dc=fripost,dc=org'.  We're also using the
default '/var/lib/ldap' as olcDbDirectory (hence we don't clear it
before hand).

We introduce a limitation on the domain-aliases: they can't have
children (e.g., lists or users) any longer.

The whole alias resolution, including catch-alls and domain aliases, is
now done in 'virtual_alias_maps'. We stop the resolution by returning a
dummy alias A -> A for mailboxes, before trying the catch-all maps.

We're still using transport_maps for lists. If it turns out to be a
bottleneck due to the high-latency coming from LDAP maps, (and the fact
that there is a single qmgr(8) daemon), we could rewrite lists to a
dummy subdomain and use a static transport_maps instead:

  virtual_alias_maps:
    mylist@example.org -> mylist#example.org@mlmmj.localhost.localdomain

  transport_maps:
    mlmmj.localhost.localdomain mlmmj:

They were only a dirty hack for list commands à la Mailman such as
mylist-request. If we are to use another list manager such as mlmmj,
which uses a VERP delimiter instead, the problem disappears.

Instead, we pretend that lists are valid users (via a match in the
mailbox_transport_maps) but choose a different transport (with the same
request in transport_maps).

The advantage is that we get rid of the ugly hack for list transport…

A minor drawback is that we now have two LDAP lookups instead of one for
non local addresses (ie, everything but reserved addresses). Hopefully
the requests are cached; but even if they aren't, querying a local LDAP
server is supposed to be cheap.

It'd certainly be nicer if we didn't have to deploy amavis' schema
everywhere, but we need the 'objectClass' in our replicates, hence they
need to be aware of the 'amavisAccount' class.