Postfix cannot send and receive emails

Postfix cannot send and receive emails-Linux general technology-Linux technology and application information. The following is a detailed description. I was able to send emails when I was just created, but I couldn't receive emails, but I couldn't send and receive emails after I modified the IP address of the local server. What is the problem? Can you provide a detailed solution!
Now I paste maillog:
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 = , 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 = , Client = 192.168.1.100, module = login, status = loginok

Newbie! I hope to give a detailed answer! Thank you!