Slower bounce-back of commit messages

It seems like sometime in the past few days, the throughput of the
PG mail system dropped substantially.  The particular symptom I'm
noticing is that when I push multiple commits, it used to be
that the pgsql-committers traffic came back (a) within a few seconds
and (b) all together.  Now it takes a few minutes for them to trickle in,
as in this example of seven commits that were pushed together:

From pgsql-committers-owner+M15-102287@lists.postgresql.org  Wed Nov 14 16:40:31 2018
 Subject: pgsql: Doc: remove claim that all \pset format options are unique in
From pgsql-committers-owner+M15-102288@lists.postgresql.org  Wed Nov 14 16:40:35 2018
 Subject: pgsql: Doc: remove claim that all \pset format options are unique in
From pgsql-committers-owner+M15-102292@lists.postgresql.org  Wed Nov 14 16:43:57 2018
 Subject: pgsql: Doc: remove claim that all \pset format options are unique in
From pgsql-committers-owner+M15-102289@lists.postgresql.org  Wed Nov 14 16:44:20 2018
 Subject: pgsql: Doc: remove claim that all \pset format options are unique in
From pgsql-committers-owner+M15-102290@lists.postgresql.org  Wed Nov 14 16:44:34 2018
 Subject: pgsql: Doc: remove claim that all \pset format options are unique in
From pgsql-committers-owner+M15-102293@lists.postgresql.org  Wed Nov 14 16:44:43 2018
 Subject: pgsql: Make psql's "\pset format" command reject non-unique
From pgsql-committers-owner+M15-102291@lists.postgresql.org  Wed Nov 14 16:44:52 2018
 Subject: pgsql: Doc: remove claim that all \pset format options are unique in

I've also noticed slower turnaround on some of the other lists.
What's up?

            regards, tom lane