apt-get install sendmail
apt-get install libsasl2-2 libsasl2-modules sasl2-bin
apt-get install dovecot-pop3d

/etc/mail/sendmail.mc 에
DAEMON_OPTIONS(`Family=inet,  Name=MTA-v4, Port=smtp, Addr=0.0.0.0')dnl
DAEMON_OPTIONS(`Family=inet,  Name=MSP-v4, Port=submission, M=Ea, Addr=0.0.0.0')dnl
로 수정하고
TRUST_AUTH_MECH(`EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
를 추가

/etc/mail/sendmailconfig 명령실행

/etc/mail/local-host-names 에 도메인 추가
/etc/mal/access 에 허용 IP대역추가
makemap hash /etc/mail/access.db < /etc/mail/access

/etc/mail/local-host-names 에 도메인 추가
/usr/lib/sasl2/Sendmail.conf 에
pwcheck_method: saslauthd 로 수정
/etc/default/saslauthd 에
START=yes로 수정

/etc/init.d/sendmail start(또는 restart)
/etc/init.d/saslauthd start(또는 restart)

/etc/dovecot/conf.d/10-auth.conf 에
disable_plaintext_auth = no
auth_mechanisms = plain login
/etc/dovecot/conf.d/10-mail.conf 에
mail_location = mbox:~/mail:INBOX=/var/mail/%u

/etc/init.d/dovecot restart
(/usr/sbin/dovecot -F -c /etc/dovecot/dovecot.conf)