Ignore the Comcast thing, that was a pure coincidence. My ISP is Comcast, but that didn't have anything to do with the NS lookup that spamassassin did. I think when it runs that test it does a random main domain or ISP (I've seen sourceforge.net, linux.org, etc). Look I did it again:
*cough*
I'll repeat myself..
" Either that or you are using comcast's nameservers, and they've decided to block access to RBLs by their users."
Are you using comcast's nameservers? If so, it is possible that they have blocked their namserver from answering queries for common RBL domains. Intentionally.
