I was getting this crazy error when sending out an email on my iPhone..
After some research, I just realize that there is a my mistake when making adjustment of /etc/postfix/main.cf
Hereby my mistake:
mynetworks = 127.0.0.0/8 113.xxx.77.xxx/32 192.168.1.0/24
Do you recognize it? Do never forget the , comma sign “,” among each parameters. So, it should be correct like this:
mynetworks = 127.0.0.0/8, 113.xxx.77.xxx/32, 192.168.1.0/24