[exim] show matcching element in hostlist

Hello,

can anybody please tell me a way to find out which element in a
(host)?list caused a match?

I'm using something like this:

hostlist sender_whitelist = CONFDIR/lists/sender_whitelist_byIP \
                          : CONFDIR/lists/sender_whitelist_byName
...

accept
  hosts    = : 127.0.0.1 : +relay_from_hosts : +sender_whitelist
  logwrite = DEBUG: SHAP CH early accepted

where the hostlists are using CIDR and regex. Everything works fine,
it's just that I would like to be able to log what matched ...

# sender_whitelist_byIP:
207.171.160.0/19
87.238.80.0/21
...

# sender_whitelist_byName:
^\S+.csx\.cam\.ac\.uk$
^\S+\.amazon\.com$
...


Many thanks

- Karl