Symptoms
Compiling sendmail.mc file in a VDS
Resolution
The usual mc compilation command is: "m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf" (DO NOT USE THIS) That command would destroy VDS mail configuration.
The right command should be:
"/usr/bin/m4 / /usr/share/sendmail/sendmail.cf/m4/cf.m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf"
Please back up the sendmail.cf file prior the compilation.