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                9:11 p.m.
            
        also thank you for this pointer here, this time a debian v12 setup saved :)
the issue after migrating lists from mailman21 to v3 and following the guide was that the index was rebuilt as root and therefore the cronjob running as www-data could not access these files - chown'ed the files to www-data and rebuilt the index as this very user - everything went fine.
thx!