I'm getting the mesage regulary inside mail.log from postfix. In special, but not only, at mails send received mailman. warning: hostname localhost does not resolve to address ::1: No address associated with hostname ::1 as well as 127.0.0.1 are defined as localhost inside /etc/hosts -- as provided by openVZ. Actually inside /etc/hosts these is configured (I removed special domains and IP for reasons): fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters 2a01::<some IPv6> host.example.org host example.org 127.0.0.1 localhost.localdomain localhost # Auto-generated hostname. Please do not remove this comment. xxx.xxx.xxx.xxx host.example.org host example.org ::1 localhost ip6-localhost ip6-loopback And this seems to work: $ host localhost localhost has address 127.0.0.1 localhost has IPv6 address ::1 On this box bley is also running.