[exim] Collecting Statistical data from a router to SQL

Hi

I would like to create a router which would collect statistical data
about the emails passing through it and update a MySQL database with
that data, the router would then pass the message on to the next
router.

Currently I cannot work out if this is even possible, I am not sure
what driver or transport to use when all I want the router todo is run
a SQL update statement and then pass the email to the next router. I
have googled read the book etc.

Can anybody point me in the right direction?

Failing that the only other option I have is to probably use a system
filter which i thought might be a bit messy.

Thanks and Regards

J-P Human