Most of us probably rely on sendmail emulation from Postfix or some other MTA. But if you need to use Webmin’s sendmail module and encounter errors while setting it up, the installation may not be complete.
For errors about a missing /etc/mail/sendmail.cf file and/or m4 command, verify that the following package is installed after installing Webmin’s module.
Name : sendmail-cf
Version : 8.15.2
Release : 32.el8
Architecture : noarch
Size : 198 k
Source : sendmail-8.15.2-32.el8.src.rpm
Repository : AppStream
Summary : The files needed to reconfigure Sendmail
URL : http://www.sendmail.org/
License : Sendmail
Description : This package includes the configuration files you need to
: generate the sendmail.cf file distributed with the sendmail
: package. You will need the sendmail-cf package if you ever need
: to reconfigure and rebuild your sendmail.cf file.
Running
dnf install sendmail-cf
actually installs two missing pieces.
(1/2): m4-1.4.18-7.el8.x86_64.rpm
(2/2): sendmail-cf-8.15.2-32.el8.noarch.rpm