correcting Sender:, From, and Return-Path:

My work network of about 12 computers has an exim 4.50 server set
up by a contractor. I don't know much about exim, and only know
enough about postfix to run my small home network. I would like
to change some settings/header information and need help.

_Summary:_
I want to change the From and Return-Path: headers to reflect
those of the original email. At present, for some reason, they
seem to be rewritten as fetchmail@example.dyndns.org . This
makes setting up vacation messages etc difficult. eg if I have a
procmail recipe like the one in procmailex man page [1], the
addresses stored in the cache and the vacation notification mails
seem are to fetchmail@example.dyndns.org, not the actual sender
of the email.

I've noticed some entries in /etc/exim4/exim4.conf under
smart_host_remote_rewrite, domain_literal_remote_rewrite,
dnslookup_remote_rewrite, remote_smtp_rewrite,
cluster_smtp_rewrite, cluster_smtp_rewrite_headersonly that may
be the ones, but not sure enough to change them and risk taking
down our server.

Can someone point me in the right direction of what settings to
change?

_Network Description:_
The exim server is on our gateway machine which has 2 NICs - one
external dynamic IP assigned by ISP, the other is 192.168.0.1
static for our internal network. We use a dyndns.org account to
resolve the external IP when needed.

Our "real" domain, say example.com.au, is hosted by a webhosting
company. We retrieve our email from them using fetchmail daemon.

[1]
-----8<-----
SHELL=/bin/sh # for other shells, this might need adjustment

:0 Whc: vacation.lock
# Perform a quick check to see if the mail was
# addressed to us
* $^To:.*\<$\LOGNAME\>
# Don't reply to daemons and mailinglists
* !^FROM_DAEMON
# Mail loops are evil
* !^X-Loop: your@own.mail.address
| formail -rD 8192 vacation.cache

:0 ehc # if the name was not in the cache
| (formail -rI"Precedence: junk" \
-A"X-Loop: your@own.mail.address" ; \
echo "I received your mail,"; \
echo "but I won't be back until Monday."; \
echo "-- "; cat $HOME/.signature \
) | $SENDMAIL -oi -t
-----8<-----

--
Troy Piggins
,-o
o ) Ubuntu linux 6.06 http://ubuntu.com RLU#415538 http://counter.li.org
`-o uptime: 08:12:49 up 8 days,37 min,2 users,load average:0.00,0.03,0.00