rDNS checks in spamd

Hello,

I notice quite a few hosts without rDNS/FCrDNS getting whitelisted by
spamd.

I reject hosts with no rDNS using the following in my crontab:

(spamdb|for i in `awk -F'|' '/GREY/{print $2}'`; do if ! host $i >/dev/null; then spamdb -dG $i; fi; done)

It works, but it does not feel like it is the best way to do it.

OpenSMTPD rejects the hosts without RCrDNS using a filter anyways, but
it feels better to know that smtpd is not talking directly to these
likely suspicious hosts.

Does it make sense to add a rDNS check option to spamd?
(if not a full FCrDNS check)
If so then I could work on it.

Thanks, Dimitrios