A frequent commenter here, Ovidiu, was just reject by spamhaus.org as being a spammer. The ip address that he used was listed in the spamhaus black list.
It turns out that he is in an ip range that denies direct email. I am going to change it so that it only checks for known spammers and just spammers.
Just to let you know: I tried a few times by connecting/reconnecting but my ISP seems to assign me a private IP so it seems they are using NAT, when that didn’t work, I tried several times through Tor proxy and ended up having to tunnel via a socks proxy via putty to my root server to be able to comment here…
anyway, thanks for looking into this matter 🙂