Am 04.01.2022 um 02:02 schrieb Ken Wright:
$ sudo chmod g+s /usr/sbin/postdrop $ ls -la /usr/sbin/postdrop -r-xr-sr-x 1 postfix postdrop 22808 Sep 7 02:58 /usr/sbin/postdropWietse, is this what's expected?
AFAICT you are lacking write permission for the user. -- Alex JOST