Basta leggere i logs:

[Mon Dec 14 08:21:25 2009] [error] [client 89.149.254.73] proxy: DNS lookup failure for: aabbo.com returned by http://aabbo.com/bbs/formmail_form.php
[Wed Dec 16 17:58:14 2009] [error] [client 89.149.254.73] proxy: Error reading from remote server returned by http://www.artnice.com.hk/formmail_contact.php, referer: http://www.artnice.com.hk/contact.php
[Thu Dec 17 12:03:30 2009] [error] [client 89.149.254.73] (70007)The timeout specified has expired: proxy: error reading status line from remote server ssrental.co.kr, referer: http://ssrental.co.kr/acecart/bin/f...ow.cgi?f_na=ss2
[Thu Dec 17 12:03:30 2009] [error] [client 89.149.254.73] proxy: Error reading from remote server returned by http://ssrental.co.kr/acecart/bin/formmailshow.cgi, referer: http://ssrental.co.kr/acecart/bin/f...ow.cgi?f_na=ss2

questi sono tre servers (aabbo.com - artnice.com.hk - ssrental.co.kr) che il tuo server sta cercando di contattare per mandare probabile SPAM.
Chissa' quanti altri sono andati a buon fine.

Attivati prima di finire nelle liste RBL e trovarti con l'IP bloccato.