In some cases you may want to temporarily turn off MX records, particularly on gateways. For example, you may want to MX everything in a domain to one machine that then forwards it directly. To do this, you might use the DNS configuration:
*.domain. IN MX 0 relay.machine
and on relay.machine use the mailertable:
.domain smtp:[gateway.domain]
この設定か？ permanent error は考えてないな……
DNSで引けるレコードを制限して… *.example.org IN MX 0 foo.example.org.
