Comcast: Human or Automaton?

Filed under The Web by adam | May 14, 2006 | 6 comments

I’m not the first person with a story about the sad state of Comcast. Since I’m certain I’m never actually going to get a True Human to read my email at Comcast, I’ll just post my brief exchange regarding Comcast’s SMTP servers here. Maybe some future archaeologist of the Internet will point to this exchange as early evidence of the End of Email:

I posted the following to Comcast’s website feedback form — apparently there is no publicly advertised email address for communicating with Comcast:

Please forward this email to an engineer responsible for Comcast’s SMTP service.

I run an ISP. Email to @comcast.net addresses often bounces with a “556 null byte in data” rejection connecting to gateway-s.comcast. I use postfix from Debian Sarge.

This is not a problem on my end. There are numerous reports of this problem in newsgroups (just google ‘556 null byte in data’ ‘comcast’). The problem is independent of mail user agent and ISP.

Note that this is *not* an issue of my users attempting to connect to the Comcast SMTP server themselves—I understand there is some issue where Comcast only accepts SMTP/SSL/TLS now for its users. This is a *delivery* problem.

I have seen some speculation that Comcast’s SMTP servers are rejecting email with this error because of either large attachments or attachments with long filenames. I have seen the problem occur where the attachments are very small (on the order of 10K), but I haven’t ruled out the latter explanation.

Please let me know if there is anything I can do to fix this problem. My users would like to be able to email Comcast customers.

Comcast’s response:

Dear Adam KESSEL,

Thank you for taking the time to write us.

Comcast is aggressive about protecting its’ subscribers from unwanted and unauthorized emails. In keeping with industry standards and best practices some recent changes to our filters have been made.If you are attempting to send emails to legitimate recipients in the Comcast.net domain, and receive an error message there are 3 likely reasons:

1. Your mail server has been identified as a source of Spam. Our mail filters have been updated to reject all mail from your server until the administrator of your mail server contacts us to request the server be removed.

2. The source of your message has a dynamic email address. Anyone attempting to email into the Comcast domain directly from a Dynamic IP address will receive the following error message:

Comcast does not support the direct connection to its mail servers from residential IPs. Your mail should be sent to comcast.net users through your ISP. Please contact your ISP or mail administrator for more information.

3. Your mail server has an invalid rDNS value. What this means is that our mail filters authenticate each message by checking the rDNS value to ensure its’ a legitimate domain and yours wasnot.

The error or “bounce” message you receive will indicate which reason the message was rejected. Youwill either be given the address to request Blacklist removal or you will be directed to our rDNS FAQpage.

If a domain administrator feels that their IP range has been blocked in error or they would like information on required steps to be removed from our black list, they can contact us at:

blacklist_comcastnet@cable.comcast.com

If you need assistance setting up email through your ISP?s mail servers please visit their support pages or contact their support group.

If you need information on the rDNS block, please visit: http://www.comcast.net/help/faq/index.jsp?faq=Email118405

Thank you for the opportunity to assist you. If you need further assistance with any of your Comcast services please reply to this email and we will be happy to assist you. Thank you again for choosing Comcast we appreciate your business. To visit our local support page including links to contact us via Live Chat, as well as many downloadable forms,and FAQ pages, please visit: http://www.comcast.com/nesupport/

Did you know that Comcast offers its customers a variety of free benefits? These include McAfee Antivirus, Firewall and Privacy software as well the Comcast tool bar that lets you take Comcast.net with you while you surf, and the Desktop Doctor to help you restore lost settings…plus much more, please visit http://www.comcast.net/downloads/ to see all of the extras that we provide.

Sincerely,
Irene

Comcast Electronic Customer Care – New England

You can email us anytime by replying to this email or by clicking the “Contact Comcast” link found on the bottom of all www.Comcast.net and www.Comcast.com webpages. Our Electronic Customer Support teams are available to assist you 24 hours a day 7 days a week.

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The response contained in this message is intended for the addressee only and may vary from other ponses depending on geography, promotional campaigns or other factors. If you are not the intended recipient of this response, please delete this message. Any unauthorized use or dissemination of the information contained in this message is prohibited.
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The last bit about “unauthorized use” is a nice touch.

My follow-up:

The 556 null byte SMTP error is *not* a spam or blocking related rejection.

My mail server is (1) not a source of spam (2) does not have a dynamic IP address (I assume below whenyou wrote “dynamic email address” you meant “dynamic IP address”); it is not a residential IP but rather a commercial ISP that I run; and (3) the mail server has a valid reverse DNS lookup.

To clarify: not every email is being rejected from the ISP’s IP address. In fact, the same sender can send from my ISP multiple times to a Comcast subscriber, and most messages will get through.

There appears to be a bug in your SMTP delivery server whereby certain triggering events cause a 556 null byte error. There is at least some evidence that one such triggering event is an email with an attachment with a long filename. This is not a spam filter issue. This is a Comcast SMTP configuration issue.

As you will see if you google “‘556 null byte in data’ comcast” this is awidespread problem that is entirely unrelated to Comcast’s zealous efforts to block unsolicited email.

Please forward my email to an engineer or technician.

Thanks,
Adam

Finally, Comcast’s witty retort:

Dear Adam Rosi-Kessel,

Thank you for taking the time to write us.

Commercial Email Accounts

We have to apologize, but at this time you must contact our Commercial Business support team by calling one of the following toll free numbers 888-824-8105 or 888-824-8155, 1-888-737-8361

Thank you for the opportunity to assist you. If you need further assistance with any of your Comcastservices please reply to this email and we will be happy to assist you. Thank you again for choosingComcast we appreciate your business. To visit our local support page including links to contact us via Live Chat, as well as many downloadable forms,and FAQ pages, please visit: http://www.comcast.com/nesupport/

Did you know that Comcast offers its customers a variety of free benefits? These include McAfee Antivirus, Firewall and Privacy software as well the Comcast tool bar that lets you take Comcast.net with you while you surf, and the Desktop Doctor to help you restore lost settings…plus much more, please visit http://www.comcast.net/downloads/ to see all of the extras that we provide.

Sincerely,
Ivonne

Comcast Electronic Customer Care – New England

You can email us anytime by replying to this email or by clicking the “Contact Comcast” link found onthe bottom of all www.Comcast.net and www.Comcast.com webpages. Our Electronic Customer Support teams are available to assist you 24 hours a day 7 days a week.

**************************************************
The response contained in this message is intended for the addressee only and may vary from other responses depending on geography, promotional campaigns or other factors. If you are not the intended recipient of this response, please delete this message. Any unauthorized use or dissemination of the information contained in this message is prohibited.
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If anyone has interesting ideas about how to get past Comcast’s front lines, I would like to know.