I am not sure if this page is correct, looks at least like this g+s not ok https://doc.dovecot.org/2.3/admin_manual/filesystem_permission/

work-around is to manually create dirs mdbox mdbox/storage mdbox/mailboxes. I would think this is a bug as files seem to be created correctly.

group rights are not copied on directories, resulting in getfacl #effective:--- for the acl groups just testing with rm -R -f everything below usertest6

[@ shared]# ls -ln
total 4 drwxr-xr-x 4 0 0 34 Sep 23 11:50 bak drwxrwx---+ 4 10001 10001 34 Sep 23 12:18 usertest drwxrwx---+ 3 10002 10002 19 Sep 23 11:51 usertest2 drwxrwx---+ 3 10006 10006 19 Sep 23 12:37 usertest6 -rw-r--r-- 1 0 0 121 Sep 23 11:46 README

where are the group rights on mdbox?

[usertest6]# ls -lartn total 0 drwxr-xr-x+ 6 0 0 84 Sep 23 11:50 .. drwxrwx---+ 3 10006 10006 19 Sep 23 12:37 . drwx------+ 2 10006 10006 30 Sep 23 12:37 mdbox

now group rights are back? [usertest6]# ls -lartn mdbox/ total 0 drwxrwx---+ 3 10006 10006 19 Sep 23 12:37 .. -rw-rw----+ 1 10006 10006 0 Sep 23 12:37 dovecot-acl-list drwx------+ 2 10006 10006 30 Sep 23 12:37 .

trying again with g+s usertest6

[usertest6]# ls -arltn total 0 drwxr-xr-x+ 6 0 0 84 Sep 23 11:50 .. drwx--S---+ 2 10006 10006 30 Sep 23 12:48 mdbox drwxrws---+ 3 10006 10006 19 Sep 23 12:48 .