Configure Courier-Authlib
Modify Authdaemonrc#vi /usr/local/etc/authlib/authdaemonrc
#
# ADD the lines like :
authmodulelist="authpam"
DEBUG_LOGIN=1
daemons=1
Modify smtpd.conf
#vi /usr/lib64/sasl2/smtpd.conf
pwcheck_method: authdaemond
log_level: 3
mech_list: PLAIN LOGIN
authdaemond_path:/usr/local/var/spool/authdaemon/socket
Modify Permission
#chown -R postfix:postfix /usr/local/var/spool/authdaemon/
#chown o+x /usr/local/var/spool/authdaemon/