Cannot open /usr/share/sendmail-cf/m4/cf.m4

2. Save a backup of the default /etc/sendmail.cf, then create new one.

cp -p /etc/sendmail.cf /etc/sendmail.cf.save
m4 /etc/mail/sendmail.mc > /etc/sendmail.cf

NOTE: If you get following error, install sendmail-cf RPM package "sendmail.mc:10: m4: Cannot open /usr/share/sendmail-cf/m4/cf.m4: No such file or directory"