xx@mxt6.test.ex router = lookuphost, transport = remote_smtp host ten-1.test.ex [V4NET.0.0.1] MX=5 myhost.test.ex@mxt1.test.ex router = self, transport = remote_smtp host myhost.test.ex [V4NET.10.10.10] xx@mxt1.test.ex router = self2, transport = remote_smtp host myhost.test.ex [V4NET.10.10.10] xx@not.exist is undeliverable: Unrouteable address