MailHops highlights the PBL => Email sent by Comcast subscribers using a client are required to send the email through Comcast | 76.16.0.0/12 is listed on the Policy Block List (PBL)

Using MailHops as noted previously.  There are always things to learn in the SMTP ecosystem.  This one was a new indication.

Indication

As seen in Thunderbird

Headers

Return-Path: <USERNAME@gmail.com>
Received: from mail-ia0-x231.google.com (ia-in-x0231.1e100.net [IPv6:2607:f8b0:4001:c02::231])
	by *.emerson.baker.org (8.14.5/8.14.5) with ESMTP id r0S0rbSO020205
	(version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=OK)
	for <USERNAME@baker.org>; Sun, 27 Jan 2013 16:53:45 -0800
Received: by mail-ia0-f177.google.com with SMTP id h8so3340757iaa.8
        for <USERNAME@baker.org>; Sun, 27 Jan 2013 16:52:33 -0800 (PST)
DKIM-Signature: <snip/>
X-Received: by 10.50.170.69 with SMTP id ak5mr3728249igc.56.1359333942594;
        Sun, 27 Jan 2013 16:45:42 -0800 (PST)
Received: from *.emerson.baker.org (c-76-A-B-C.hsd1.ca.comcast.net. [76.A.B.C])
        by mx.google.com with ESMTPS id df6sm4868980igb.15.2013.01.27.16.45.41
        (version=TLSv1 cipher=RC4-SHA bits=128/128);
        Sun, 27 Jan 2013 16:45:42 -0800 (PST)
Message-ID: <5105CA34.4050306@gmail.com>
Date: Sun, 27 Jan 2013 16:45:40 -0800
From: USERNAME <USERNAME@gmail.com>
User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121016 Thunderbird/16.0.1
MIME-Version: 1.0
To: "USERNAME" <USERNAME@baker.org>

Details

Via: PBL1523206

76.16.0.0/12 is listed on the Policy Block List (PBL)

Outbound Email Policy of Comcast for this IP range:
Email sent by Comcast subscribers using a mail program such as Outlook Express are required to send the email through Comcast. To insure your mail program is properly configured, please visit Email117481. If you are a Comcast Commercial Services customer and need support, please contact support_biz@cable.comcast.com

<snip/>

For full information on how the PBL operates please see the PBL Home page and the PBL Frequently Asked Questions.

Notes

SpamHaus

Comcast