套件：postfix安裝：#yum install postfix
設定檔：/etc/postfix/main.cf
inet_interfaces = all
mydomain = a234.snpy.org
myhostname = a234.snpy.org
mydestination = a234.snpy.org , b.twbbs.org
mynetworks_style = subnet 網段Relay
smtpd_sasl_auth_enable = yes (SMTP驗證)
smtpd_sasl_security_options = noanonymous
smtpd_sasl_local_domain = $myhostname
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions =
permit_sasl_authenticated,
permit_mynetworks,
check_relay_domains
服務：dovecot & saslauthd & named啟動
#service postfix restart
檢查：#postconf -d (查看設定檔)
message_size_limit = 1024000 -> 1M發送大小
mailbox_size_limit = 1024000 -> 10M容量
smtp_recipient_limit = 1000 -> 收信人數
補充：/etc/dovecot.conf (當uid&gid為0時,可以允許發送mail)
first_valid_uid = 0
first_valid_gid = 0
