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Comcast blocking AWS, Digital Ocean emails?

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Comcast blocking AWS, Digital Ocean emails?

Hello,

 

It appears that as of last week, Comcast is blocking email from at least two service providers: AWS and Digital Ocean. Bouncebacks return with "550 5.1.0 Connection is not being accepted at this time." This can be reproduced via a telnet session to the Comcast mail servers and the connection will return the error noted above after "MAIL FROM:".

I've confirmed:

- sending IPs are not blocked by Comcast (multiple hosts tested)

- sending domains are not blocked by Comcast (different domains have been tested)

- SPF/DKIM/PTR records are valid.

 

Any help would be greatly appreciated.

Tags (3)
Expert

Re: Comcast blocking AWS, Digital Ocean emails?

Are you sure they are sending to the correct address?  Usually, the 550 series error messages indicate something is wrong with the recipient email address.



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New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

Yes, the recipient Comcast email addresses all exist. The errors occur at the "MAIL FROM:"  stage of sending a message, which is prior to the recipient's address.

Official Employee

Re: Comcast blocking AWS, Digital Ocean emails?

Feel free to share your sending IP(s) and domain(s).  We can take a closer look.


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New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

Thank you - I have sent you a Private Message.

New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

I'm seeing this same issue from another Digital Ocean VM. I've got SPF configured property, DKIM configured property and rDNS also configured properly. My VMs IP address is not on any well-known spam blacklists, that I'm aware of.  And I've already tried to de-list my VMs IP address with the Comcast  but merely get:

 

"Blocklist Removal Response: After investigating the issue, we have found that the IP you provided for removal is currently not on our blocklist"

New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

I've also sent a PM with my IP information.

New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

Thank you again! This has now been resolved and I can get passed the "MAIL FROM:" portion of sending an email, and successfully send/receive to my Comcast email address from AWS server.

Regular Visitor

Re: Comcast blocking AWS, Digital Ocean emails?

Hello,

 

How did you resolved this issue ? can you help me please , i m facing the same problem with AWS

 

Thank you

Contributor

Re: Comcast blocking AWS, Digital Ocean emails?

I whole heartily support this, Digital Ocean was a source of the majority of Spam emails.  

New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

My son can no longer send emails to my comcast email.  This started about 1 month ago.  We think this is due to the blocking.  How can I get his email address added to the "whitelist"?  I can private message his email address.

Official Employee

Re: Comcast blocking AWS, Digital Ocean emails?

I just need the domain of his email address if you're willing to share that.  Then I can do some research into what might be going on.  Thanks


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New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

He uses a private domain that I don't want to share publically.  Can I send it privately?

Official Employee

Re: Comcast blocking AWS, Digital Ocean emails?

I mean, sure, but domains are public knowledge.


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New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

After trading private messages the issue has been resolved.  I received a test message from my son and he longer gets the error message.  Nice quick fix.  Thanks!

Tags (1)
New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

I'm encountering the same issue.

 

IP is 35.153.110.174.

Domain is lists.midrange.com

 

Error is:

Dec 29 17:50:30 listmail postfix/smtp[28326]: B08146239B: to=<someuser@comcast.net>, relay=mx1.comcast.net[96.114.157.80]:25, delay=6.5, delays=0.51/4.9/0.6/0.54, dsn=5.1.0, status=bounced (host mx1.comcast.net[96.114.157.80] said: 550 5.1.0 Connection is not being accepted at this time. (in reply to MAIL FROM command))

New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

I'm facing the same problem

 

unifiedoregon.com is the domain

 

Mark

New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

We're having similar issues and use AWS.  Our use case uses email  from addresses with the domains @riverstar.com and @nicor.com.  

 

I'm also requesting that reverse DNS resolves to our servername.riverstar.com.  (Currently reverse DNS resolves to something like ec2-123-45-67-89.compute-1.amazonaws.com.)    Will that help this issue?

New Poster

Re: Comcast blocking AWS, Digital Ocean emails?


@JConneely wrote:

I'm also requesting that reverse DNS resolves to our servername.riverstar.com.  (Currently reverse DNS resolves to something like ec2-123-45-67-89.compute-1.amazonaws.com.)    Will that help this issue?


That will help a lot in general. Are you messages getting blocked outright, deferred, nor is there an indication that you're on a block list? If they are getting blocked outright, you may have to talk to Comcast email security people about getting your IP allowed. If you're getting indication of a block list, there is an online form you can use (http://postmaster.comcast.net/block-removal-request.html). In my case, the IP was blocked outright and requesting removal from their RBL did no good, because it wasn't on the RBL.
Official Employee

Re: Comcast blocking AWS, Digital Ocean emails?

@JConneely  I'm going to send you a private message.  I see a few things going on that I'm not quite sure what you're trying to accomplish.  Yes, setting your PTR to a proper value will help because it's a better identifier of the sending system.  Please also gather your sending IPs from AWS, as I may need those for further investigation.


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New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

Hello:

 

I am having an issue with mail sent to me from an address xxxxx@beco-technic.com in Germany.  These messages are legitimate and only once made it to my spam folder.  What can I do?

New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

I'm having the same problem.  Server hosted in AWS.  Domains are @oaktreepeak.com and @silverspore.com.  Hasd worked for years and reverse DNS has been correct for years as well.

 

Attempting to go to http://postmaster.comcast.net/block-removal-request.html results in a "504 Gateway Timeout" error.

 

So I can't send to anyone on Comcast, including much of my family.

 

 

New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

Can you take a look at mine.

 

home.ischaefer.com

54.152.96.218

Multiple domain names, but mainly ischaefer.com.

 

Thanks

Official Employee

Re: Comcast blocking AWS, Digital Ocean emails?

Please try now


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New Poster

Re: Comcast blocking AWS, Digital Ocean emails?

Can you check mine too please?

 

3.18.45.165
consumercapitalnet.com