> On Mar 9, 2018, at 7:23 AM, Nikolai Dahlem <f-post...@dahlem-marten.de> wrote: > > I run a local instance of unbound for dns caching
Good. > Below is postconf -n output: > > milter_default_action = accept > milter_protocol = 6 > non_smtpd_milters = $smtpd_milters > smtpd_milters = inet:127.0.0.1:8891 Everything else looks rather vanilla, so the next thing to look for is latency in the milter. What does this milter do? Also check your syslog configuration, make sure it is not syncing the log file to disk on every write. -- Viktor.