exim configuration: smarthost and address rewriting

[Richard Cobbe <richard.cobbe@comcast.net>]

Greetings, all.

I'm having a little difficulty with exim configuration.  Debian stable,
exim 3.35-1woody2.

This is a home system, set up to deliver all outgoing mail through a
smarthost.  I ran eximconfig, selected the smarthost option, and entered
the relevant data to get my basic exim.conf file.  Since then, I've made
the following changes:

*** exim.conf.orig	Fri Apr 23 06:56:48 2004
--- exim.conf	Fri Apr 23 07:08:00 2004
***************
*** 29,35 ****
  # domain to unqualified sender addresses, specify the recipient domain here.
  # If this option is not set, the qualify_domain value is used.
  
! # qualify_recipient =
  
  # Specify your local domains as a colon-separated list here. If this option
  # is not set (i.e. not mentioned in the configuration file), the
--- 29,35 ----
  # domain to unqualified sender addresses, specify the recipient domain here.
  # If this option is not set, the qualify_domain value is used.
  
! qualify_recipient = localhost
  
  # Specify your local domains as a colon-separated list here. If this option
  # is not set (i.e. not mentioned in the configuration file), the
***************
*** 40,46 ****
  # are no local domains; not setting it at all causes the default value (the
  # setting of qualify_recipient) to be used.
  
! local_domains = localhost:comcast.net
  
  # Allow mail addressed to our hostname, or to our IP address.
  
--- 40,46 ----
  # are no local domains; not setting it at all causes the default value (the
  # setting of qualify_recipient) to be used.
  
! local_domains = localhost:home.rcc
  
  # Allow mail addressed to our hostname, or to our IP address.
  
***************
*** 413,418 ****
--- 413,420 ----
  # don't have their own domain, but could be useful for anyone.
  # It looks up the real address of all local users in a file
  
+ cobbe@comcast.net    richard.cobbe@comcast.net h
+ 
  *@comcast.net    ${lookup{$1}lsearch{/etc/email-addresses}\
  						{$value}fail} frFs
  


There's another hunk enabling authenticated connections, required by my
smarthost, but I'm omitting that here to avoid broadcasting my passwords
to all and sundry.  I don't think it's relevant to my question, in any
case.

I should point out that I have (deliberately) given my machine a bogus
hostname, nanny-ogg.home.rcc, to avoid collisions.  And my user name on
my local machine is `cobbe'.

In general, all of this works correctly.  Mail that I send from cobbe's
account is correctly routed through the smarthost to its destination,
and it is labeled as coming from the address richard.cobbe@comcast.net,
which is the desired result.  Additionally, mail that is sent to
root is handled according to the local alias file, *not* routed up to
root@comcast.net (who, I'm sure, really doesn't want my logcheck output).

There's just one minor fly in the ointment left: mail that is sent from
root@localhost (as by logcheck, for instance) is rewritten to appear as
coming from root@comcast.net.  I'd really like to have exim configured
to leave sender addresses of root@localhost alone, but it's not clear to
me from the Exim manual how to disable the qualify_domain rewriting for
a single local address.

Could anyone point me in the right direction, please?

Thanks very much for any help,

Richard