yum install sendmail sendmail-cf
# vi /etc/mail/sendmail.mc
TRUST_AUTH_MECH(`EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN‘)dnl
define(`confAUTH_MECHANISMS‘, `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN‘)dnl
DAEMON_OPTIONS(`Port=smtp,Addr=0.0.0.0, Name=MTA‘)dnl
# m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf
systemctl start sendmail.server
yum install sendmail sendmail-cf
yum install dovecot cyrus-sasl cyrus-sasl-md5 cyrus-sasl-plain cyrus-sasl-lib
TRUST_AUTH_MECH(`EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN‘)dnl
define(`confAUTH_MECHANISMS‘, `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN‘)dnl
define(`confAUTH_OPTIONS‘, `A p‘)dnl
define(`confCACERT_PATH‘, `/etc/pki/tls/certs‘)dnl
define(`confCACERT‘, `/etc/pki/tls/certs/ca-bundle.crt‘)dnl
define(`confSERVER_CERT‘, `/etc/pki/tls/certs/sendmail.pem‘)dnl
define(`confSERVER_KEY‘, `/etc/pki/tls/certs/sendmail.pem‘)dnl
DAEMON_OPTIONS(`Port=smtp,Addr=0.0.0.0, Name=MTA‘)dnl
原文：http://guowang327.blog.51cto.com/6513732/1729403