On 12 Jun 2017, at 2.09, M. Balridge <dove...@r.paypc.com> wrote: > >> I think it's just doing a lot of work on the mbox file itself >> (reading/writing/rewriting). Would be nice of course if it logged >> more information, but mbox format is a bit too legacy to spend >> much time on improving. > > I suspect the (heavy) use of procmail on Herr Frankbox is contributing to > either some lock "confusion" *OR* triggering dovecot to do "expensive" mbox > re-read/syncs or something?
Have you set mbox_very_dirty_syncs=yes? That should be helpful.