[[Open Terminal as root|As root]]:
{{Code|<nowiki>SMTP_SERVER=your_isp_smtp_server</nowiki>
yum -y install sendmail-cf m4
cd /etc/mail
sed -ie <nowiki>"s/.*SMART_HOST.*/define(\`SMART_HOST', \`$SMTP_SERVER')dnl/"</nowiki> sendmail.mc
make
service sendmail restart}}