[exim] Outbound IP Address

Hi all,

I am toiling trying to set the outbound IP address (fo bandwidth accounting
reasons), and have this so far:

remote_smtp:
        driver = smtp
        helo_data = ${lookup 
dnsdb{defer_never,ptr=$sender_address_domain}{$value{$primary_hostname}}
        interface = ${lookup 
dnsdb{defer_never,a=$sender_address_domain}{$value}{my.ip.host.here}}
        return_path_add = true
        debug_print = "XX T: remote_smtp for $local_part@$domain Sent VIA 
${lookup \
                        dnsdb{defer_never,a=$sender_address_domain} \
                        {$value}{my.host.ip.here}} XX"

It seems to work ok if a virtual user logs in and sends an email to an
outside server, it goes through OK and seemd to be reporting the right
(outgoing) ip.

However, if a mail comes into the server, addressed to an address that is an
alias to another server (and domain), it fails miserably saying that 'can't
assign requested address'. I am thinking that it is seeing the original
sender's domain and trying to assing it as the outgoing address.

Does anyone have any ideas here? ( or will I need to make another pair of
remote_smtp Routers/Transports).

-Grant