[exim] Setting the HELO response at a per-interface level

Hi everyone,

I've recently set up a new server running Exim 4.60, however this server
has two network interfaces, with a different FQDN for each interface.
I've noticed that whenever Exim sends mail out through either interface
it always uses the machine's primary hostname, instead of the hostname
belonging to the interface it's connecting out of.

For example, interface one has an IP of 1.1.1.1 with a hostname of
one.example.com, and interface two has an IP of 2.2.2.2 with a hostname
of two.example.com. Sending out of the first interface gives this line
in the e-mail:

Received: from one.example.com ([1.1.1.1])

Which is fine, but sending out of interface two gives this line:

Received: from two.example.com ([2.2.2.2] helo=one.example.com)

Evidently the receiving instance of Exim notices that the HELO response
doesn't match the IP address and lists it in the headers. From looking
at the list archives there have been a fair few people who've also come
across this problem, but most of those messages were sent before 2002 -
I couldn't find anything much recently. I did find one message saying
it was on the wishlist for Exim 3...

So does anyone know whether this is now possible? I realise that it
does no harm leaving it this way, but it would be "nicer" to have HELO
send the correct hostname.

Thanks,
Adam.