mkdir /etc/mail/cert
cd /etc/mail/cert

openssl genrsa -des3 -out server.key 1024
openssl rsa -in server.key -out server.key.open
openssl req -new -x509 -days 3650 -key server.key.open -out server.crt
chmod 600 server.*

vi /etc/mail/sendmail.cf
O CACertPath=/etc/mail/cert
O CACertFile=/etc/mail/cert/server.crt
O ServerCertFile=/etc/mail/cert/server.crt
O ServerKeyFile=/etc/mail/cert/server.key.open
O ClientKeyFile=/etc/mail/cert/server.crt

/etc/init.d/sendmail restart