最近在使用国内的服务器的时候经常会发现这个问题
其实问题很简单，就是默认来说，国内的服务器没有IPv6， 而postfix 的默认配置文件是有Ipv6的，因为就会出现下面的warning:
send-mail: warning: inet_protocols: IPv6 support is disabled: Address family not supported by protocol
send-mail: warning: inet_protocols: configuring for IPv4 support only
postdrop: warning: inet_protocols: IPv6 support is disabled: Address family not supported by protocol
postdrop: warning: inet_protocols: configuring for IPv4 support only
知道问题的出处，解决就简单多了，默认让postfix 只monitor IPv4就可以了
编辑/etc/postfix/main.cf
将
inet_protocols = all
改成
inet_protocols = ipv4就完美解决了