Before building sendmail, we need to create users, groups and directories that sendmail uses with the following commands: groupadd smmsp && groupadd mail && useradd -g smmsp -G mail smmsp && chmod 1777 /tmp && chmod 1777 /var/mail && mkdir /var/spool/mqueue Install sendmail with the following commands: cat > devtools/Site/site.config.m4 << "EOF" define(`confMANGRP',`root') define(`confMANOWN',`root') define(`confSBINGRP',`root') define(`confUBINGRP',`root') define(`confUBINOWN',`root') EOF cd sendmail && sh Build && cd ../cf/cf && cp generic-linux.mc sendmail.mc && mkdir /etc/mail && sh Build sendmail.mc && sh Build install-cf && cd ../../ && sh Build install