Tonight, an email to a friend of mine was rejected from the mail servers, sent back with a notice that my mail server has been blacklisted by the good folks at Comcast “for abuse.”

----- The following addresses had permanent fatal errors -----
(my cousin's email address)
(reason: 550- blocked by ldap:ou=rblmx,dc=comcast,dc=net)
----- Transcript of session follows -----
... while talking to
MAIL From: (my email address) SIZE=4602
<<< 550- blocked by ldap:ou=rblmx,dc=comcast,dc=net
<<< 550 Blocked for abuse. Please send blacklist removal requests to - Be sure to include your mail server IP ADDRESS.
554 5.0.0 Service unavailable

I administer my own mail server, and can tell you with absolute certainty that it’s not involved in any abuse directed the way of Comcast, so this was a bit confusing. I sent off an email to the address in the response, providing the information that was requested and asking for an explanation.

Hello -- I just tried to send an email from my mail server to a colleague on, and received a reply that my mail server has been blacklisted. (I am the administrator of the mail server; it's, also known as, IP address Can I please learn why the server has been blacklisted? I'd appreciate logs of any suspicious activity that you've seen, if that's the cause of the blacklist.
Please get back to me at your soonest convenience; this is actually a reasonably large problem.
Thank you.

I then went to my good friend Google to see if I could better understand what had happened, and learned that I’m far from the only one who’s experienced this idiocy. Hidden-Tech appears to have been blacklisted regularly, as has HSH Associates, TechPro, and even the esteemed Wil Wheaton (hell, the TechPro people had to have their attorney participate in phonecalls to Comcast before they were able to get the problem solved!). After reading those, it didn’t surprise me at all to hear my email notification ding and find this in my inbox:

Please do not reply to this message.
We have received your request for removal from our inbound blacklist. After investigating the issue, we have found that you did not include the IP address to be removed.
We need the IP address that you believe is currently blocked to further investigate this issue.
Please verify the IP and resubmit your request to

So, what I’ve learned is that not only does Comcast suck at administering its own email system, it sucks at the simple task of writing a tiny app to find an IP address in an email. It’s unfortunate that both my inlaws rely on Comcast for their email addresses — I guess it’s time to move them over to something a bit more competently-managed.

Update: I sent another email, this time with the IP address alone on its own line, and again got a reply saying I didn’t send the address. I hate Comcast; maybe it’s time to just block all incoming email from and be done with it.

Update 2: I sent two more emails, trying to decipher the super-secret method Comcast’s using to find the IP address (on a blank line? prefixed by “IP ADDRESS”? on the subject line?), and both garnered replies that claimed I didn’t include it. Seriously, this is the most broken system I’ve encountered on the ‘net ever; Comcast has just essentially guaranteed that I’d rather pith myself than ever become a customer of theirs.


Funny (well, no, it’s not), I was just blacklisted from that venerable host, AOL. According to them I was not allowed to send anyone with an AOL address email because “someone had complained” about mail sent from my server. I am not in the spam-sending biz and who knows who else is on my shared server.

I waited for it to resolve itself but finally contacted my Web host who simply routed my email through another one of their servers (and one which is not on their blackball, I mean blacklist).

• Posted by: Jeff [TypeKey Profile Page] on Mar 1, 2006, 12:31 PM

Yep, I ran into this at my employer, with 3 domains hosted on a shared server. The bosses’ first reaction was to ask that I move to a different host, but after I pointed out the problems others have had with comcast, cooler heads prevailed. Eventually (like 3 weeks), the host got off the blacklist. It looks like they’re at it again, however. I ran across this message posted on my host’s message board yesterday:
“I just wanted to let everyone know that the blocks on Comcast, Hotmail, and a few other services are occurring because of a recent change to their spam policies. They both use a service called Brightmail for spam protection. The change on their network was made without warning and our efforts to have the blocks lifted have only been temporarily successful. We have contacted the mail server vendor (SmarterTools) in regards to the problem and they are currently working on a patch that will alleviate this issue. We will keep working with Hotmail, Comcast, and Brightmail however; there may be intermittent blocks for different mail servers until the error is ultimately resolved by the patch.”

• Posted by: Steve A on Mar 1, 2006, 3:37 PM

Ditto here - I’ve sent 5 emails to them in various syntax trying to get the magic formula & I think it’s a lost cause w/them.

The “no IP included” emails I get back from them include the following:

“If you have any additional questions, you may contact us at 856.317.7272.”

If you try calling the number provided it rolls into a voice mail system saying to leave contact info and they will call you back within 24 hrs. They are now 2 hrs past that for my call.

I think I’m gonna go back to pen, paper & stamps. ;-P

• Posted by: JeffB on Mar 8, 2006, 1:57 PM

Same here. We are a Law Firm with heavy anti-virus and anti-spyware/spam solutions in place and yet we have been blacklisted by Comcast. I tried calling their Internet support group at 888-252-6300 several times and each time it rings about 25 times then the line is disconnected. I sent an email to but have not received a response. We are preparing to sue Comcast for loss of revenue due to their heavy handed and apparently quite random blacklisting policy which is prohibiting our Firm from communicating with our clients who unfortunately use Comcast’s email service. We will see if/how they respond to that.

• Posted by: th on Mar 10, 2006, 1:55 PM

Got the same problem… No luck.

Just a word to the idiot above who obviously knows nothing about the law. I AM actually an attorney and you can’t sue for lost revenue. That remedy is only available when an agreement was made beforehand. Also, you don’t have a contractual relationship like that with comcast, because they don’t give them out.

Stop being an idiot and try to actually help find a way to resolve the issue

• Posted by: scott trendor on Mar 29, 2006, 10:07 AM

I put the IP address in the subject line.. no message back yet!

• Posted by: Maeghan on Apr 7, 2006, 11:09 AM

I was able to use the email just fine. Try putting square brackets around the IP address in the body of the message (ie. []). I received a response in under 3 hours that my IP had been removed from their rblmx list. Hope this helps!

• Posted by: Cameron Moore on Apr 19, 2006, 4:23 PM
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