deliver to remote SMTP

Unrouteable address

1pjpwb-001BkR-Ir <= root@node5.lan.example.com U=root P=local S=13815
1pjpwb-001BkR-Ir ** root@node5.lan.example.com: Unrouteable address

When configured as smarthost, local exim4 rejects sender address node5.lan.example.com because domain is not real. Solution is to add:

/etc/exim4/update-exim4.conf.conf
dc_other_hostnames='node5.lan.example.com'

so complete file:

/etc/exim4/update-exim4.conf.conf
dc_eximconfig_configtype='internet'
dc_other_hostnames='node5.lan.example.com'
dc_local_interfaces='127.0.0.1 ; ::1'
dc_readhost='node5.lan.example.com'
dc_relay_domains=''
dc_minimaldns='false'
dc_relay_nets=''
dc_smarthost='smtp.example.com::465'
CFILEMODE='644'
dc_use_split_config='false'
dc_hide_mailname='true'
dc_mailname_in_oh='true'
dc_localdelivery='mail_spool'

and execute update-exim4.conf