Some useful Sendmail commands on Slackware.
Working with MC and CF files.
To edit the default /etc/mail/sendmail.cf
cd /usr/share/sendmail/cf/cf
cp sendmail-slackware.mc sendmail-new.mc
vim sendmail-new.mc
cp sendmail-slackware.mc sendmail-new.mc
vim sendmail-new.mc
Make the desired changes and save the file. Issue these commands to create the cf file and copy it to /etc/mail.
m4 sendmail-new.mc > sendmail-new.cf
cp sendmail-new.cf /etc/mail/sendmail.cf
cp sendmail-new.cf /etc/mail/sendmail.cf
Multiple Domains
Make sure your sendmail-new.mc above includes
FEATURE(`use_cw_file')dnl'
Then edit /etc/mail/local-host-names and add the domains to it.
example.org
mail.example.org
www.example.org
mail.example.org
www.example.org