Apparent BIND problem doing RBL lookups for Postfix

[Nuno Paquete]

Greg,

Usually we use forwarders so we don't always have to bother root
servers. 
Because our ISP's deals with great amount of requests from all the
clients, probably most of your new requests are already in their cache
and it's much faster than query a root server, because it's on the same
network.
I mentioned the forwarders parameter because it's usual to use our ISP's
dns servers as a forwarder and I thought you might had a misconfigured
forwarder.
Although you have forwarders configured, from the point of view of your
dns clients your dns server still answers the requests the same way, and
if you have a problem with your dns server, the problem still remains,
so, you are not putting the problem away.

> Well, using forwarders might fix "general" bind errors, but it's
> likely to run into problems for RBL lookups at spamhaus.org - since
they have
> limits (100K SMTP connects a day, and 300K lookups)
> So using my ISP's name servers which have higher volume is likely to
> run afoul of those limits because it's aggregating traffic. Even if
> it doesn't right now, it could at any time when someone else does the
> same and that increase in lookups pushes us over the edge.

I don't think so. All the requests to spamhaus.org will be made by your
postfix box, not from your forwarders. 
And look, your server only queries forwarders when its own cache
expired, before that your server answers the queries by himself, without
bothering forwarders.
I use spamhaus.org with postfix/spamassassin and I've got no problem
with it.

Best Regards,
Nuno Paquete