1.开启加密，雷鸟中设置为加密
[root@server79 ~]# postconf -d | grep ^smtpd_tls
[root@server79 ~]# postconf  -e smtpd_tls_security_level = encrypt( 验证时必须走加密)
postfix reload
[root@server79 ~]# telnet localhost 25
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 server79.example.com ESMTP Postfix
ehlo localhost
250-server79.example.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-STARTTLS    //表明已经启动了加密算法
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN

2.制作证书
[root@server79 certs]# make postfix.pem
[root@server79 certs]# cp postfix.pem /etc/postfix/
[root@server79 certs]# postconf -e smtpd_tls_cert_file=/etc/postfix/postfix.pem
[root@server79 certs]# postconf -e "smtpd_tls_session_cache_database = btree:/var/lib/postfix/smtpd_scache"

3.雷鸟邮箱设置
setting->Outgoing Server-Edit->servername 192.168.0.179,port 25,connection security:STARTTLS,Authentication method:Normal password,User Name:cun@extmail.org