skip_hosts — skip the specified host, but consider other hosts in the domain
skip_hosts = ("127.0.0.1")
skip_hosts = ("127.0.0.1" "fe80::a00:1")
Skip_hosts does not permanently deny a domain. Instead, it enables you to skip the specified host but still consider other hosts in the domain. For example, to prevent delivery to loopback addresses (127.0.0.0/8) or the null route 0.0.0.0, you can use the following line:
skip_hosts = ( "127.0.0.0/8" "0.0.0.0" )
Note: This setting does not affect where you receive mail from, only where you can deliver mail to.
skip_hosts is valid in the global scope.