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From: Wolfgang Agnes <wagnes@jemoni.to>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: sendmail questions: setgid bit, mail.local et cetera
Date: Tue, 05 Nov 2024 17:33:05 -0300
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I have a fresh install of FreeBSD-RELEASE 14.0 done by my service
provider, which I upgraded to FreeBSD-RELEASE 14.1 yesterday (with help
from people here, in fact).

%uname -a
FreeBSD my.host.name 14.1-RELEASE-p5 FreeBSD 14.1-RELEASE-p5 GENERIC amd64

I'm reviewing sendmail configuration and I came to check whether my
sendmail had its setuid bit set.  I discovered it does not.  But then I
thought I'd find it had the setgid bit set.  It also does not.

%ls -l $(which sendmail)
lrwxr-xr-x  1 root wheel 11 Nov 10  2023 /usr/sbin/sendmail -> mailwrapper

%ls -l $(which mailwrapper)
-r-xr-xr-x  1 root wheel 8648 Nov  4 22:34 /usr/sbin/mailwrapper

So I guess the FreeBSD designers compiled sendmail with a default group,
which must be ``mail'', which is the group in /var/mail, so that must be
how sendmail is able to deliver messages to local users.

I expected to find the program mail.local---for local mail delivery.  I
do not find this program on root's path, but I find its manual page in
section 8.  Should I not have this program?  Where is it?  

I'm reading the book

  sendmail
  Bryan Costales, George Jansen, 
  and Claus Afsmann with Gregory Neil Shapiro
  O'Reilly, fourth edition, 2008, ISBN 978-0-596-51029-9

and they talk about mail.local as the program that delivers local mail.