Currently, this happens:<p><pre><code>   if hostname != target {
      downstream.Write([]byte(&quot;452 Different domain, please reconnect and deliver separately.\r\n&quot;))
      continue
   } else {
</code></pre>
As a side-effect, email to the secondary domain is slightly delayed.<p>It is a full proxy, in the sense that it sees all of the traffic, so technically it could de-multiplex and spool to two different targets at the same time for the duration of the current email..  Hasn&#x27;t been a noticeable problem so far.  But it would be nice to add at a later point in time.  If&#x2F;when someone complains, probably.