#修改postfix配置
vi /etc/postfix/main.cf

#增加一行
message_size_limit = 104857600

#重启postfix

#centos 6
/etc/init.d/postfix restart

#centos 7
systemctl restart postfix

#如果报错 postfix: fatal: parameter inet_interfaces: no local interface found for ::1
#all改为ipv4
inet_protocols = ipv4