Comment (by Roland Haas):

Ok, turns out that apparently one had to use “google.com” and could not use “.google.com” to match all Google subdomains even though the man page on the server (and the web, https://linuxlasse.net/linux/howtos/Blacklist_and_Whitelist_with_Postfix) indicate that “.google.com” is the way to do and that “google.com” is a backwards compatible way that will go away eventually. So:

> cat /etc/postfix/google_access
google.com OK

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2362/et-mailing-list-spam-filter-occasionally