[Exim] Limiting messages per N hours

Greetings all,

I'm investgating how we might limit the number of emails per period that our
exim server may forward to particular domains, or addresses.

What we are doing is, on a per application basis, having severe or fatal
problems ('disk full', etc) emailed to appropriate mobile phones via an sms
gateway. However as contacts and systems increase in number, we need to move
the throttle from the (many) applications to the mail server such that exim
will, for instance, forward the first two such mails in every 6 hours, on the
third send a prearranged message ('3 or more severe problems, please contact
the office') and discard fourth and subsequent mails. (A maillist will
already have sent emails to people's iboxes, so the thrid and subsequents are
not completely lost).

The soothing side for domestic harmony is obviously far more important than
anything else!

I've not been able to google up anything like the above, or see anything in
the docs under 'limit' or 'throttle'. Before I knock something up in perl, is
anyone here aware of anything in Exim that already provides the above?

Many thanks,
- --
Alistair Mann