The AHBL blacklist (rhsbl.ahbl.org, dnsbl.ahbl.org, and ircbl.ahbl.org) ceased operations on 01.01.2015. All requests to the blacklists are answered positively, which causes SPAM filters to classify the mail as SPAM. So if you have still entered the blacklist, you should correct the configuration as soon as possible.
Click here for information from AHBL:
http://www.ahbl.org/content/last-notice-wildcarding-services-jan-1st
How to configure the blacklists for Exchange 2010 is described here:
