[exim] Technique for preventing multiple email addresses bei…

Hi,
I am receiving SMTP traffic sent to me from many guests in hotel through
automatic SMTP redirection.
We have a system whereby the hotel is allowed to send 'From' up to 200
different email addresses each day.
This works fine for the most part.
Sometimes, though, a problem occurs. Someone using the hotel's IP address
sends out a single spam email from 200 different email 'From' addresses
within the space of about 10 minutes. This uses up the hotel's entire quota.
My question is this: does Exim have some sort of built-in mechanism that can
cope with, say, limiting the number of different email addresses that are
allowed to be used by a particular IP address, per time period (e.g. 1
hour).
Or is that asking way too much?
Thanks