I just started a new job and I was given the task of fixing a blacklist issue

I work for a library that sends out notices to people via email about late charges, holds on accounts, things like that. I have already sent an email off to eathlink to have them take us off the spam list, and I looked at www.mxtoolbox.com and removed a few of our IP's from NOMOREFUNN, and our service provider is Charter. What I am noticing is that our DNS IP addresses are coming back as being on 11 lists, and they all say wa.charter.com. Is there anything else we can do to try to fix this problem ourselves?

When we try to send to any Earthlink or PeoplePC account we get this error:

Delivery has failed to these recipients or distribution lists:

XXXXXXXXX@peoplepc.com
A communication failure occurred during the delivery of this message. Microsoft Exchange will not try to redeliver this message for you. Please try resending this message later, or provide the following diagnostic text to your system administrator.

Diagnostic information for administrators:

Generating server: XXXXXXX.XXX.XXX

terryldnl@peoplepc.com
#< #5.5.0 smtp;550 550 Dynamic/zombied/spam IPs blocked. Write blockedbyearthlink@abuse.earthlink.net> #SMTP#

Original message headers:

Received: from XXXXX ([192.168.XX.XX]) by XXXXXX.XXX.XXX with Microsoft
 SMTPSVC(6.0.3790.3959);       Thu, 7 Aug 2008 06:00:38 -0700
MIME-Version: 1.0
From: <automated@XXX.XXX>
To: <XXXXXXX@peoplepc.com>
Reply-To: <do-not-reply@XXX.XXX>
Date: Thu, 7 Aug 2008 06:00:38 -0700
Subject: Library notice
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
Return-Path: automated@XXX.XXX
Message-ID: <XXXXXQx67PjrU3ciMDr000015d6@XXXXXXX.XXXX.XXX>
X-OriginalArrivalTime: 07 Aug 2008 13:00:38.0700 (UTC) FILETIME=[96F86EC0:01C8F88D]Start Free Trial