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Mivid004
1st Topic

2 Messages

Tuesday, January 14th, 2025 8:02 PM

Email issue sending to Comcast Emails

We have a client of ours that is having issues emailing Comcast email addresses via bulk emails. Every other recipient receives the emails, but Comcast bounces back. We have DKIM, SPF, and DMARC configured correctly on the domain but still receive the error below. I call Comcast support and they said the end users have blocked the emails, which is incorrect, because they receive email when it is sent directly to use user, it has become very frustrating. Below is the error that is received. 

Reason: [{LED=451 4.2.0 Throttled - https://postmaster.comcast.net/smtp-error-codes.php#RL000010};{MSG=};{FQDN=mx2.mxge.comcast.net};{IP=2001:558:fd02:243f::5};{LRT=1/9/2025 8:02:35 PM}]. OutboundProxyTargetIP: 2001:558:fd02:243f::5. OutboundProxyTargetHostName: mx2.mxge.comcast.net

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Updated 

3 months ago

189

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0

XfinityKei

Official Employee

 • 

1.4K Messages

3 months ago

@Mivid004 I’m sorry to hear your client is having an issue with sending emails to Comcast email users. Now we have some limitations, and I'm wondering if they're the reason the issue is happening. Comcast blocks certain file extensions that are often associated with spam or harmful software. The following email attachment types are not allowed:

  • .vbs
  • .pif
  • .scr
  • .bat
  • .com
  • .cmd
  • .msi
  • .reg
  • .exe

 

Comcast has put the following sending limits in place for our residential Xfinity Internet customers:

  • An email message can be sent to a maximum of 100 recipients.
  • Any messages sent to over 100 recipients will not be delivered.
  • Xfinity customers can email up to 1,000 recipients per day. If an account exceeds the 1,000-recipient limit, the account will not be able to send for the remainder of the day.
  • The maximum size of an email cannot exceed 25 MB; this includes attachments, headers, text, formatting, etc.

Do the emails fall into any of the above? 

 

2

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Mivid004

2 Messages

The emails do not have any file attachments and does not fall into any of the above. I can provide more information if requested. The domain is beavercountybar.net

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3 months ago

0

XfinityAdrienne

Official Employee

 • 

1.2K Messages

Thank you so much for sharing those details with us, Mivid004! I was digging into the details a bit further, and want to ensure, have you reached out to our Customer Security Assurance Team? They can be reached here if not, and they can help look into the domain and the bounce back concerns. 

 

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3 months ago

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