I am sorry. This is not in the FAQ. This is in the README.
ATTENTION: this mechanism won't work for you if you specify fidonet-style
address as the "visible name" in your MTA. Do not do it! Even if you
don't have an official Internet domain, use something.uucp as your
primary machine name, NOT fN.nM.zL.fidonet.org.
Probably I should have stated clearly that this does not only apply to
'visible name' but to any 'localname'. The idea is that your fidonet
domain shall not be distinguished as local in your MTA.