make -C /etc/mail/
In Debian you can get the next error.
make: Entering directory '/etc/mail' Updating databases ... Reading configuration from /etc/mail/sendmail.conf. Validating configuration. Creating /etc/mail/databases... Could not open /usr/share/sendmail-cf/m4/cf.m4(No such file or directory) .....
The error is related to a wrong path (/usr/share/sendmail-cf) in several config files in /etc/mail.
To solve identify all the config files with the wrong line.
grep -R sendmail-cf /etc/mail
After that you can fix the places it shows up with the correct path /usr/share/sendmail/cf.