foo@mx-sec-a-aa.test.ex
  router = dnslookup, transport = smtp
  host a-aa.test.ex [V4NET.0.0.100] MX=5
foo@mx-aa-a-sec.test.ex
  router = dnslookup, transport = smtp
  host a-sec.test.ex [V4NET.0.0.100] MX=5