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This is my first post here, and I sure hope you guys can help me out - this seems to be where the really good Comcast techies hang out.
I have a Comcast business account with a static IP (188.8.131.52) for my domain mccci.com. I run my own mail servers (along with web and other servers). I do not relay via or use Comcast mail servers. Everything has worked fine until the end of July, I started receiving PTR errors for emails addressed to Comcast.net recipients. At that time NO other emails were bouncing, just Comcast.net, since then Gmail.com and a couple of others have started bouncing with a similar error.
This is a sample of the error I'm getting, with email addresses XXXX'd out:
The original message was received at Fri, 2 Oct 2015 17:41:46 -0400 from [10.1.1.70]
----- The following addresses had permanent fatal errors ----- <XXXXXXX@comcast.net>
(reason: 554 resimta-ch2-02v.sys.comcast.net comcast 2601:183:c302:8f00:1240:5ff:fe6a:2fee Comcast requires t... requirement. For more information, refer to: http://postmaster.comcast.net/smtp-error-codes.php#554)
----- Transcript of session follows ----- ... while talking to mx1.comcast.net.:
<<< 554 resimta-po-15v.sys.comcast.net comcast 2601:183:c302:8f00:1240:5ff:fe6a:2fee Comcast requires that all mail servers must have a PTR record with a valid Reverse DNS entry. Currently your mail server does not fill that requirement. For more information, refer to: http://postmaster.comcast.net/smtp-error-codes.php#554
... while talking to mx2.comcast.net.:
<<< 554 resimta-ch2-02v.sys.comcast.net comcast 2601:183:c302:8f00:1240:5ff:fe6a:2fee Comcast requires that all mail servers must have a PTR record with a valid Reverse DNS entry. Currently your mail server does not fill that requirement. For more information, refer to: http://postmaster.comcast.net/smtp-error-codes.php#554
554 5.0.0 Service unavailable
I opened a ticket with Tech Support (NA0000175633308), which yielded nothing. I didn't have time to waste on this in August, but in early September opened a second ticket (can't find the ticket number). This guy insisted that my PTR record was wrong, and told me I should fix it. I told him YOU (Comcast) own the PTR records so if there is a problem YOU (Comcast) need to fix it. He didn't seem to understand any of this, and referred me to Comcast Security Assurance. I spoke with them briefly, they insisted that the PTR record(s) for my IP were fine, sent me back to Tech Support.
I reached one fellow in Tech Support who was really, really bright - he totally got what the problem was. We did a series of tests, and he set up a couple of additional PTR records. The most interesting test is that when I send him email a Comcast.COM it goes through fine, but when I would email to his Comcast.NET email address it would be blocked with the PTR error message - so clearly the .COM and .NET servers aren't configured the same or the problem would show up on both.
The bottom line is that for 2 months now I've been unable to send emails to Comcast.net users, and now Gmail.com is complaining with a similar message:
The original message was received at Thu, 1 Oct 2015 09:29:54 -0400 from [10.1.1.70]
----- The following addresses had permanent fatal errors ----- <XXXXXXXXX @gmail.com>
(reason: 550-5.7.1 [2601:183:c302:8f00:1240:5ff:fe6a:2fee] Our system has detected that)
----- Transcript of session follows ----- ... while talking to alt1.gmail-smtp-in.l.google.com.:
<<< 550-5.7.1 [2601:183:c302:8f00:1240:5ff:fe6a:2fee] Our system has detected that <<< 550-5.7.1 this message does not meet IPv6 sending guidelines regarding PTR <<< 550-5.7.1 records and authentication. Please review <<< 550-5.7.1 https://support.google.com/mail/?p=ipv6_authentication_error for more <<< 550 5.7.1 information. o65si5254729qki.3 - gsmtp
554 5.0.0 Service unavailable
My gut feeling tells me that this is an IPV6 problem, and that the PTR records Comcast set up for my IP don't work with IPV6. I actually disabled IPV6 in my Linux server as a test today and it seemed to work (emails made it through to Gmail), but other problems started showing up so I backed off that change (the other problems may have just been a coincidence).
Is there a Comcast Tech (or anybody else!) out there that can help me?
Solved! Go to solution
Not on any block lists.
The message you posted tells you the cause.
all mail servers must have a PTR record with a valid Reverse DNS entry. Currently your mail server does not fill that requirement.
It could be as you think IPv6 call comcast business if you have a business account
You should be posting in the business class forums. This is residential.
Thanks, I didn't know there was a Business Class forum, And lo and behold now everyone with an IPV4 static IP is having the same problem as me because Comcast is not issuing corresponding IPV6 static IPs!!!!!
So WHY doesn't anybody at Comcast Tech Support know about this, and why have I been chasing my tail for 2 months trying to figure this out?!?!?
I'll continue the discussion over there I guess, in the meantime looks like forcing my Linux server into IPV4-only might do the trick.
The problem comes in because you call into Residential services. They rarely know about the Help and Support forums here, nevermind knowing what Business class services offers as far as help and support goes.
No, I never call Residential Tech Support, these were opened with Business Services.
Like I said I did reach one fellow who was on the right track, but couldn't figure out the problem.
Meanwhile, one guy (I believe he was in Security Assurance) was literally arguing with me that I needed to "update my PTR records", and could not grasp that COMCAST owns and configures the PTR records (no matter how many times I explained it to him).
The one good thing that came out of this is that I found these forums (residential and business class), I never knew they existed and there are some helpful threads here.
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