title: Specify remote port to use for mail via exim4
body: <p>I've got a stock Debian Etch system, using Exim4.  The domains are mostly local but there are some that are remote. To handle the delivery of remote mail I use the Debian configuration file:</p>
  
  <pre><code>  /etc/exim4/hubbed_hosts
  </code></pre>
  
  <p>This file lists the domain names, and remote MX machines to deliver to.  For example:</p>
  
  <pre><code>  example.org:  mx.example.com
    example.com:  mx2.example.com
  </code></pre>
  
  <p>Looking at the exim4 configuration file I see that this used as follows:</p>
  
  <pre><code>hubbed_hosts:
    debug_print = "R: hubbed_hosts for $domain"
    driver = manualroute
    domains = "${if exists{CONFDIR/hubbed_hosts}\
                     {partial-lsearch;CONFDIR/hubbed_hosts}\
                fail}"
    route_data = ${lookup{$domain}partial-lsearch{CONFDIR/hubbed_hosts}}
    transport = remote_smtp
  </code></pre>
  
  <p>The issue I have is that <em>some</em> of the hosts I'm using need to have their mail delivered to a non-standard port.  Unfortunately the Debian hubbed_hosts file doesn't work if I try to change it to include a port:</p>
  
  <pre><code>example.org: mx1.example.org:2525
  example.com: 1.2.3.4.2525
  </code></pre>
  
  <p>Is it possible to dynamically allow the port to be specified?</p>