Comments on: Comcast Blocking Mail to Comcast Addresses

By: MadScienceLab LLC

MadScienceLab LLC — Sat, 31 Dec 2011 22:23:43 +0000

This loss of signal and spam blocking actually sounds like a user on the system that is spamming. (Have you possibly checked to see if there is a ghost user on your system causing this? WiFi users see this problem all the time in the city where there is a confluence of people and an unlocked wireless signal! First thing to do, check your users. Second, try sending mail from a different mailbox on the same server, telnet sessions may get bounced from comcast servers because they dont want you telnetting into thier smtp server. lol (Which ironically may cause you to get your whole domain blocked)

By: AC

AC — Tue, 15 Nov 2011 22:40:48 +0000

Oh yeah, I forgot: SPF is good to help prevent spammers from forging your email domain… but it’s not perfect at all other facets of fighting spam.

NEVER enable SPF on your domain if you send email from random hotspots, or you use the “free” email provided by your ISP, or you “forward” your mailbox from one mailserver to another (like from your company mailserver to gmail, etc). If you enable SPF in these conditions, you don’t know what SPF really means and you will be asking other sites to delete or spam score your email.

By: AC

AC — Tue, 15 Nov 2011 22:33:45 +0000

I for one am GLAD Comcast blocks outbound port 25 from their users. You obviously are not, but that’s because you don’t suffer a deluge of illegitimate traffic that is 99.99% of dynamic/non-static/dialup/too-clueless-to-configure-a-PTR-on-your-mailserver.

If you want to send mail, get yourself a static IP and learn how to configure a PTR. OR gateway your email through a real mailserver (Google ‘what is a SmartHost’ to learn more).

If you don’t – that’s your choice – but you’re literally standing in the middle of a pack of zombie systems and then deluding yourself why you’re getting labeled as a bad apple. You’re probably running an Exchange configuration which auto-replies to spam, sending it back to the forged “From:” address (this is an actual default configuration in Exchange).

By: Gary

Gary — Thu, 14 Oct 2010 17:47:21 +0000

I’m having a similiar issue. I can’t sent to comcast.net e-mail accounts from any of 5 or 6 domains I’ve tested. They are not on any RBL and Comcast says they are not blocked.

I don’t get any indication that the recipients are not getting my e-mails, no bounces, etc., just goes into a blackhole. Comcast can’t seem to figure it out. Frustrating.

By: Jacob Burch

Jacob Burch — Wed, 21 Jul 2010 16:16:18 +0000

This is probably because your PTR records are mismatched, please check your reverse DNS.

By: Miya

Miya — Tue, 14 Jul 2009 01:08:03 +0000

I am having the same issue as “Werner” above. I am simply having all incoming email from my work email address forwarded to my Comcast email address. Starting Sunday, anybody that emailed my work email addy got the error message displayed above from Comcast. I submitted my work’s email server IP to Comcast and they say it’s not blocked and are no help further than that. Great.

By: Werner

Werner — Tue, 12 May 2009 22:46:49 +0000

But none of this applies to my problem. I am not sending mail from anyone but comcast. I am forwarding any emails I get from my ISP to my comcast address. I get the same bounce back message shown above. And I got the same response from comcast when I sent in a request to unblock my IP (IP not blocked). Then I looked at the error code (554) and entered that into Comcast support page. It is not a direct block of Spam but a claim that they require Reverse DNS and that my ISP has not configured Reverse DNS on that email server. When I tell my ISP this they say it is a comcast problem (pointing me to this blog) and say goodbye.

Does anyone have any good ideas about resloving this without spending another 24 hours on the phone?

Thanks!

By: Scott

Scott — Fri, 01 May 2009 13:02:55 +0000

Yep, you’re right, I remember now, and we stopped using SPF altogether almost 18 months ago on our servers because it was such a pain. Every once in a while, some user needs SPF turned on, and in those cases, we do have to add the Comcast info.

By: Kevin Mooney

Kevin Mooney — Fri, 01 May 2009 02:01:18 +0000

I’ve had the same experience. Great tech support in Michigan, lousy in Seattle.

By: Angry SEO

Angry SEO — Wed, 29 Apr 2009 21:54:40 +0000

Totally inconsistent across the company, these policies. Fricken Internet Nazis. On another note, SPAMMERS break the world again. Unreal what we have to go through just to address a core exploit of the Internet, Spam.