Quoting Mike Bird (mgb-devuan@???):

> I've been running mail servers and mailing lists for more than two
> decades.
>
> Rick if you can give Rowland specific times (+timezone) of some
> bounces that would assist Rowland's admins in finding the actual
> reason for the bounces in his mail server's logs.

Thank you, Mike, for attempting to help.

As I've mentioned upthread, I am a (friendly) _outsider_ to Dyne.org, who
runs and administers Mailman and MTAs elsewhere -- and as such have no
access to Dyne's MTA and MLM logs (nor samba.org's MTA logs). The best
help I could think of to give Rowland was to strongly suggest that he
contact the sysadmin teams (not the listadmns) of the hosts involved.

FWIW, Mailman listadmins cannot produce the timestamps of 'bounce'
events unless they are also shell users. I assist Dyne.org's listadmins
on some matters, and know that at least one of those listadmins lacks
shell access (and would speculate that the others do, too). As I
mentioned, reading MTA logs typically requires root shell, while Mailman
logs merely require shell.

I wish Rowland luck, but will not be assisting further with this
problem. (If you can think of a way for Dyne.org's listadmin to look up
'bounce' timestamps without host shell access, please help them do so.
Thanks.)