You can also log in to the chroot environment and do try to execute some commands like telnet, mtr to see if networking is working as expected.
2016-10-17 18:14 GMT+01:00 Wietse Venema <wie...@porcupine.org>: > ????? ?????: > > Postfix 3.1.1 > > > > > disable_dns_lookups = no > > > lmtp_host_lookup = dns > > > smtp_host_lookup = dns > > > disable_dns_lookups = no > > > > > > # diff /etc/nsswitch.conf /var/spool/postfix/etc/nsswitch.conf | wc -l > > > 0 > > If chroot makes a difference, then you have some file difference. > > There are more files that determine host lookups. The first one > that comes to mind is resolv.conf. > > Also don't overlook file/directory permission differences. > > Wietse >