[Exim] smtp_accept_max_per_host excepions

smtp_accept_max_per_host is fantastic, and we've seen it catch aggressive
spammers on our main mail farms. Record in just a few days after turning it
on is 30k over-limit connection attempts in 2 hours from a dialup!

However, these same mail farms are used by some internal servers as
smarthosts, and quite often, we want to allow them to have more concurrent
connections than the default limits imposed on everyone else.

Would it be possible to have an exemption list for connection limits, or
perhaps make available an expansion variable so that one could use if
statements or lookups to determine connection limits?

Cheers.