But then I received it again, yesterday. The very same message! I have no idea why. Email is a Mysterious Medium.
I think they restarted the mailing list server; I got that message and a handful of other messages, which apparently never got cleared from the mail queue or something. And IIRC shortly before the resends, someone in #haskell was asking if there were problems with the mailing lists.
(this kind of stuff is why I got out of the business of running mail servers)