Si lors de l'installation de amavis vous affichez ce message :
Starting amavisd: head: cannot open `/etc/mailname' for reading: No such file or directory The value of variable $myhostname is "iceberg", but should have been a fully qualified domain name; perhaps uname(3) did not provide such. You must explicitly assign a FQDN of this host to variable $myhostname in /etc/amavis/conf.d/05-node_id, or fix what uname(3) provides as a host's network name! (failed).
Il vous suffit tout simplement de lancer cette commande (en remplaçant exemple.tld par votre domaine) :
echo mail.exemple.tld > /etc/mailname
  Puis de redemarrer amavis :
/etc/init.d/amavis restart
  Et le tour est joué ;)