We can therefore spare some lookups on the MDA, and use static:all
instead.

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).

That is, don't put a leading virtual_ or a trailing _maps in file names.

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:

It has to be performed last, to give a chance to be accepted as a
regular mailbox.

We introduce a new, dedicated, smtpd daemon whose only purpose is to
resolve catch-alls.

Antispam & antivirus, using ClamAV and SpamAssassin through Amavisd-new.
Each user has his/her amavis preferences, and own Bayes filter (to
maximize privacy).

One question remains, though: how to set spamassassin's trusted_networks
/ internal_networks / msa_networks? It seems not obivious to get it
write with IPSec and dynamic IPs.
(Cf. https://wiki.apache.org/spamassassin/AwlWrongWay)

Other abreviations are upper case.