Emails still bouncing....Will Comcast ever manage to fix this blacklisting issue?

Has there been any effort to get Comcast's mail servers off the blacklists that they have been stuck on for so long? We are still having immediate bounceback issues thanks to other mail servers rejecting Comcast's mail server IP. How is this a business class email service if the problem persists, and the best way to tell you is via this forum?