> On Jul 14, 2017, at 8:40 AM, Tom Hudson <tom.hud...@giacom.com> wrote: > > Thank you for all of your help so far with this issue. > > Just to let you know, the problem appears to have been caused by the > "daemon_timeout" being set far too low during our initial configuration. I > know the default in postfix is 18000s but ours had been set to 60s! > Increasing this to 600s appears to have caused the problem to go away. > > Again, thank you all for your help.
Even 600s is far too short. This is a last resort safety mechanism that should never happen, not an routine operational timeout. Set it to at least 1 hour, or better yet, just leave at the default 5 hours. -- Viktor.