[Exim] Usage per Domain per period

Greetings

A search for HOWTO's on mail usage per domain/user per period has
returned tons of links in various search engines but nothing useful. I
am convinced that my little dilemma has been resolved by someone:

What I need to be able to do is generate a usage report per domain &
user for a specific period for billing purposes (normally from the 1st
to the 31st of each month)

Any pointers, ideas, URLS etc would be greatly appreciated.


R e g a r d s

M i c h a e l L G r i f f i n