[exim] Multiple smarthosts and archiving all emails

Hi,



I'm setting up an archiving system that will store any email entering or
leaving the local network.



Any 'forward all mail' options in the existing mail servers/relays do
just that forward a copy to another mailbox - so all envelope details
are lost. I want to be able to store the emails depending on the 'from'
and 'rcpt-to' addresses in the envelope (so we catch BCCs and mailing
list recipients and such).



A simple implementation I can think of is to stick a box between the
final spam filter gateway and the rest of the LAN - relaying mail
between this gateway and the users' mail server and have this do the
archiving.



To keep the envelope data, rather than have it drop the email into
mailboxes, I was thinking of have it SMTP a second copy of each email to
another box which processes each mail coming in directly - so having
access to the envelope data. Another benefit of doing the processing on
a separate box is that there is a lot of traffic and I don't want to put
to much more processing load in the company's email stream.



So I was thinking that the easiest way to set this up would be to
configure this intermediate Exim relay with two smarthosts that forward
on each incoming email to both smarthosts at the same time. But I don't
know if this is possible?



Any thoughts on this or another method?



Many thanks,

Steve