postfix不能收发邮件

在刚刚建立的时候是能发邮件，但是不能接收邮件，而在修改了本机服务器的IP之后就不能收发邮件了，请问这是怎么回事阿？能不能给个详细的解决方案！
现在我把maillog贴出来：
hostname
Jun 9 13:44:08 mail postfix/smtpd[4971]: connect from unknown[220.181.12.69]
Jun 9 13:44:08 mail postfix/smtpd[4971]: fatal: bad net/mask pattern: "172.16.1.0/255"
Jun 9 13:44:09 mail postfix/master[4356]: warning: process /usr/local/postfix/libexec/smtpd pid 4971 exit status 1
Jun 9 13:44:09 mail postfix/master[4356]: warning: /usr/local/postfix/libexec/smtpd: bad command startup -- throttling
Jun 9 13:51:23 mail authdaemond: stopping authdaemond children
Jun 9 13:52:55 mail authdaemond: modules="authmysql", daemons=10
Jun 9 13:52:55 mail authdaemond: Installing libauthmysql
Jun 9 13:52:56 mail authdaemond: Installation complete: authmysql
Jun 9 13:54:26 mail extmail[4023]: user=<kai.liu@njdongguan.com>, client=192.168.1.100, module=login, status=loginok
Jun 9 14:47:13 mail authdaemond: stopping authdaemond children
Jun 9 14:48:44 mail authdaemond: modules="authmysql", daemons=10
Jun 9 14:48:44 mail authdaemond: Installing libauthmysql
Jun 9 14:48:44 mail authdaemond: Installation complete: authmysql
Jun 9 14:50:40 mail extmail[3961]: user=<kai.liu@njdongguan.com>, client=192.168.1.100, module=login, status=loginok

新手上路，荆棘满地阿！希望会的给个详细的答案！谢谢！