在　/etc/postfix/main.cf　里一定要改成下面这样

mydestination =”$myhostname,localhost.$mydomain,$mydomain,mail.$mydomain, www.$mydomain, ftp.$mydomain,yourhostname.$mydomain,180.186.4.52,123.456.75.23″
relay_domains = $mydestination
180.186.4.52 这个是服务器本身的IP

#relayhost = 123.147.201.95
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 123.456.75.23

看到这个　123.456.75.23了没，把它替换成你发送端的IP