[Exim] Mail routing based on MySQL and local_part

This is a multipart message in MIME format.
--
[ Picked text/plain from multipart/alternative ]
I am in the process of converting from sendmail to
Exim4.34+SA+ExiScanACL+ClamAV.

The way my current sendmail setup works is that we have a large number of
virtual users.

E-mail comes in name@??? and via our virtual users we remap these
users to name@??? and name@???.

What we'd like to do is remap/route these messages to the appropriate
servers via a MySQL call (select newdomain from domains where name =
$local_part and domain = $domain), then send the message to
name@???.

Can anyone please help me work out how to do this or point me to a HOWTO
or something?

Thanks!
Dan Anderson
--