[exim] av_scanner blacklist

Google and Exim forum searches have failed me.

I'm scanning all inbound emails with the av_scanner options coupled with
an ACL that rejects virus infected emails. Though some servers are
apparently ignoring the 550 error and continue retrying delivery. I want
to blacklist these servers, after two or more failed delivery attempts.

Is there a way to do this from within Exim, or am I better advised to
throw together a script which, via cron, parses my rejectlog every
minute and builds a blacklist?

Thanks,
Gregg Berkholtz