I found this in my default exim.conf on my debian boks.
######################################################################
# REWRITE CONFIGURATION #
######################################################################
# These rewriters make sure the mail messages appear to have originated
# from the real mail-reading host.
*@vash ${1}@??? Ffr
*@localhost ${1}@??? Ffr
# This rewriting rule is particularly useful for dialup users who
# 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
*@vash ${lookup{$1}lsearch{/etc/email-addresses}\
{$value}fail} frFs
the contents of /etc/email-addresses are:
vash:/etc/exim# less ../email-addresses
# This is /etc/email-addresses. It is part of the exim package
#
# This file contains email addresses to use for outgoing mail. Any local
# part not in here will be qualified by the system domain as normal.
#
# It should contain lines of the form:
#
#user: someone@???
#otheruser: someoneelse@???
root: jbendtsen@???
but still no rewrite seem to be done when i send email using mutt from
this host
JonB