[vox-tech] DNS MX Record Woes

[Marc Elliot Hall]

I've been running my own web, mail, and (internal) DNS servers for 
several years now, but never before have I had an email rejected by 
the recipient's mail server for DNS reasons. However, yesterday the 
craigslist.org mail forwarder decided that my packets were unworthy 
of sending on to the final recipient. 

The message bounced, and I got this from my mail server:

============================
                        The Postfix program

<job-302677684 at craigslist.org>: host mxi2s.craigslist.org[66.150.243.2] said:
    554 <adsl-70-129-38-126.dsl.stlsmo.swbell.net[70.129.38.126]>: Client host
    rejected: Please use SMTP relay of your ISP or setup non-generic DNS (in
    reply to RCPT TO command)

[-- Attachment #2: Delivery error report --]
[-- Type: message/delivery-status, Encoding: 7bit, Size: 0.4K --]

Reporting-MTA: dns; mail.hallmarc.net
Arrival-Date: Thu, 26 Apr 2007 08:27:28 -0500 (CDT)

Final-Recipient: rfc822; job-302677684 at craigslist.org
Action: failed
Status: 5.0.0
Diagnostic-Code: X-Postfix; host mxi2s.craigslist.org[66.150.243.2] said: 554
    <adsl-70-129-38-126.dsl.stlsmo.swbell.net[70.129.38.126]>: Client host
    rejected: Please use SMTP relay of your ISP or setup non-generic DNS (in
    reply to RCPT TO command)

[-- Attachment #3: Undelivered Message --]
[-- Type: message/rfc822, Encoding: 7bit, Size: 3.4K --]
<message snipped>
============================

Yes, I'm running these servers out of my basement over ADSL with a
static IP. 

When I check all my DNS settings (external DNS for this domain is
handled by register.com), I don't see any problems -- even dnsreport.com
and mxtoolbox.com agree that my settings are good. 

Except: reverse lookups apparently are showing
adsl-70-129-38-126.dsl.stlsmo.swbell.net instead of mail.hallmarc.net.
Unfortunately, I can't seem to find a setting to configure via
register.com (and swbell.net, where the problem probably lies, is worse 
than useless). 

Google reveals that I am not the only person to see this issue with
craigslist, but doesn't provide any applicable solutions. 

Any advice?

-- 
Marc Elliot Hall
www.hallmarc.net