Loggin original ip address in relay connection

[Emanuel]

Hi,  i use exim locally, with an smarthost through Postfix. It's 
possible add in the log the real IP the real client?

Actually i only see the IP of the relay connection.
Nov 27 10:23:59 smarthost01 postfix/cleanup[18611]: 0F4F8180058A1: 
warning: header From: Emanuel <eman...@ddomain.com> from 
server.backend[172.17.110.155]; from=<> to=<eman...@recipient.com> 
proto=ESMTP helo=<c001-dr.dattaweb.com>

Regards.!!