email error on Microsoft Outlook: not delivered, delayed, then failed

What should I do or who do I contact (DSL provider or ISP provider) to get some support if not an Avast issue???

Here is what I’m getting since I’ve installed Avast 4.8 Professional two weeks ago:
(I changed part of the email address for privacy, but it was right when it was sent)
"This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

ctaylor@XXXX.com
retry timeout exceeded

------ This is a copy of the message, including all the headers. ------
------ The body of the message is 1170930 characters long; only the first
------ 106496 or so are included here.

Return-path: pro-pac@XXX.net
Received: from [69.69.168.140] (helo=propac)
by elasmtp-banded.atl.sa.earthlink.net with esmtpa (Exim 4.67)
(envelope-from pro-pac@XXX.net)
id 1KGx2a-00080M-BP
for ctaylor@XXXX.com; Thu, 10 Jul 2008 10:23:04 -0400
From: “Pro-Pac” pro-pac@XXXX.net
To: “‘Chad Taylor’” ctaylor@XXX.com
Subject: BOL of B & T Lge w/40Med
Date: Thu, 10 Jul 2008 10:22:37 -0400
Message-ID: 4CF80B4FD6B94F35BC9A58EF1C0CEE3C@propac
MIME-Version: 1.0
Content-Type: multipart/mixed;
boundary=“----=_NextPart_000_000C_01C8E276.E0C58B00”
X-Mailer: Microsoft Office Outlook 11
Thread-Index: AcjimGb5CErhiRVoRQ+9uVgAEn4FfA==
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5512

This is a multi-part message in MIME format.

------=_NextPart_000_000C_01C8E276.E0C58B00
Content-Type: multipart/alternative;
boundary=“----=_NextPart_001_000D_01C8E276.E0C58B00”

------=_NextPart_001_000D_01C8E276.E0C58B00
Content-Type: text/plain;
charset=“us-ascii”
Content-Transfer-Encoding: 7bit

See attached.

Dennis

If you’re using GMail, take a look here: http://forum.avast.com/index.php?topic=10428.0 to see how to set up secure email with avast!.
Otherwise, are you sure it’s not a problem with that particular email address you’re trying to send a message to?

Make sure your not exceeding a file size restriction.
Check with your ISP what the max. file size your allowed to send.