x@[abcd::dcba]
  router = r0, transport = t1
  host [abcd::dcba] [abcd::dcba]
x@[IPv6:cba::abc]
  router = r0, transport = t1
  host [ipv6:cba::abc] [cba::abc]
x@[abcd::dcba]
  router = r3, transport = t1
x@[IPv6:cba::abc]
  router = r3, transport = t1
220 myhost.test.ex ESMTP Exim x.yz Tue, 2 Mar 1999 09:44:33 +0000
250 OK
250 Accepted
250 Accepted
221 myhost.test.ex closing connection