AOL blocking DynDNS Mailhop-Outbound

[Rich Braun]

I finally have the proof I need...a bounceback message from DynDNS MailHop's
server, showing that AOL is explicitly blocking mail that I attempt to send
out.

AOL's rejection code is cited as 554 RLY:B1... "This error message is a
dynamic block on our system. Dynamic blocks are placed on an IP address when
the IP's statistics break our threshold. These are automated blocks that are
removed by the system within 24 hours once the complaints are again below the
threshold."

Maybe MailHop's address 205.188.146.194 is the target of AOL's filter, but the
evidence more likely points to their filtering software looking beyond the
relay server to examine headers (such as Received or X-Originating-IP) to find
other reasons to reject a message.  My own IP address appears at least twice
in the first few lines of headers.

It's really frustrating but I thought I'd pass this along to provide more
direct evidence that even a leading company like DynDNS which makes a lot of
its money providing legit mail-relay services can't quite deliver mail
properly in this day and age of overzealous spam control.  What I /wish/
DynDNS would do is strip such IP addresses from outbound headers (they aren't
put there by Postfix on my end) and replace them with a customer-ID string. 
But unless they get a lot of complaints from other customers, I'm not sure
they'll do that.

-rich

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:

  [redacted]@aol.com
    SMTP error from remote mail server after initial connection:
    host mailin-04.mx.aol.com [205.188.146.194]: 554 5.7.1 :
    (RLY:B1) http://postmaster.info.aol.com/errors/554rlyb1.html
------ This is a copy of the message, including all the headers. ------

Return-path: <richb-RBmg6HWzfGThzJAekONQAQ at public.gmane.org>
Received: from c-76-24-16-109.hsd1.ma.comcast.net ([76.24.16.109]
helo=pioneer.ci.net)
        by mho-01-ewr.mailhop.org with esmtpsa (TLSv1:AES256-SHA:256)
        (Exim 4.68)
        (envelope-from <richb-RBmg6HWzfGThzJAekONQAQ at public.gmane.org>)
        id 1PFTkU-0007Lf-L6
        for (redacted)@aol.com; Mon, 08 Nov 2010 15:35:10 +0000
X-Mail-Handler: MailHop Outbound by DynDNS
X-Originating-IP: 76.24.16.109
X-Report-Abuse-To: abuse-yJRlmlznMY/QT0dZR+AlfA at public.gmane.org (see
http://www.dyndns.com/services/mailhop/outbound_abuse.html for abuse reporting
information)