On Thu 2017-11-30 22:53:55 +0000, Laurent Bercot wrote:
>   In the past year, or sometimes at an older time than that, a lot of
> addresses have apparently failed enough probes and been unsubscribed,
> even still working addresses. Only today was it brought to my
> attention.

This kind of mass unsubscription is often due to DMARC.

please see:

   https://wiki.list.org/DEV/DMARC

for a description of how the mailman folks describe the problem and how
they deal with it.

I think the skarnet lists are probably running ezmlm, i don't know that
toolchain well enough to suggest a way to resolve the issue.

    --dkg