Emails to comcast.net addresses throttled

I run an email server behind a static IP address associated with a Comcast Business Internet account. This server has been running behind this address for over 6 years. When sending emails to comcast.net addresses lately, they are being delayed, and I'm seeing the following message returned from Comcast's server:

421 4.2.0 x.x.x.x throttled - try again later. please see http://postmaster.comcast.net/smtp-error-codes.php#rl000001

Where x.x.x.x is our static IP address.

Our SenderScore is 0. We are a small business, and do not send any type of marketing emails. According to the link above, we should be able to send 1,200 messages per hour with a Sender Score of 0. We don't even send that many emails in a month! This issues usually occurs when an email is sent to the same group of people, with around 4 having comcast.net addresses. Emails to comcast.net addresses are not sent every day, and may only be sent a few times per day.

We do not have any issues sending emails to any other domains, including yahoo.com, outlook.com and gmail.com, the issue is only with comcast.net addresses.

I suspect the issue is with the flawed Sender Score system. We have a low score because we don't have the volume of a large corporation, not because we send spam. We shouldn't be throttled for that reason!

I've called the Comcast Customer Security Assurance 4 times now, but they have not been very helpful. Can anyone else from Comcast assist with getting our IP address whitelisted, so we can send emails to comcast.net addresses without an issue?

Thank you

Responses

Comcast_Gabriel

Official Employee

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294 Messages

3 years ago

Hi! Thanks for reaching out over our forums page. I am sorry to learn about the issue you're experiencing with sending emails to https://comca.st/3m63KQa addresses. This is definitely not the experience we like to hear about. I can understand how important it is to be able to send emails without any issues for your business. We can certainly help. To research this further, would you mind sending us a private message with your name, address, and account number by clicking the "message" icon in the upper right page of any forum page? Once you click on that, input our shared handle Comcast Business to send us a private message.

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user_da1b61

New Contributor

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1 Message

3 years ago

We are having the same problem. We are trying to send just 5 emails and they just keep getting sent back to the email server with a message that the emails are being throttled. We normally probable send 20 emails to people at comcast.net a month. Can someone there please help. I have filled out the blacklist form but the answer is that we are NOT being blacklisted. Yet the emails sit in our queue with the throttled message. My email address is: tsg@cctg.com if you need to contact me directly. Thank you for your help.

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Comcast_MartinA

Official Employee

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34 Messages

Thank you, @user_da1b61 for reaching out to us over our Business Forums. We would be more than happy to take a look at your account to see what may be causing this issue. Please send us a direct message.

To send a "Peer to peer" / "Private chat message" message to "Comcast Business":

Click "Sign In" if necessary
Click the "Peer to peer chat" icon or https://comca.st/33Igi7Q
Click the "New message" (pencil and paper) icon
The "To:" line prompts you to "Type the name of a person". Instead, type "Comcast Business" there
- As you are typing a drop-down list appears. Select "Comcast Business" from that list
- An "Comcast Business" graphic replaces the "To:" line
Type your message in the text area near the bottom of the window
Press Enter to send it"

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3 years ago

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user_b8188e

New Contributor

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3 Messages

3 years ago

Comcast has been no help with this issue, and it has not been resolved for me. Each time I called the Comcast Customer Security Assurance, the issue was supposed to be escalated, but I still have not heard back from anyone.

I had the same result with the blacklist form.

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user_b8188e

New Contributor

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3 Messages

3 years ago

I also sent a private message, as Gabe suggested, but that team seemed to be even less knowledgeable than the Comcast Customer Security Assurance. They said they were opening a case, but I never heard back on that case either.

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CC_PeterC

Problem solver

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17 Messages

Hello @user_b8188e I'm so sorry to hear that no one has followed up on the case, but I can definitely take a look to see what's going on. Please send us a Live Chat with your first and last name as well as your service address so we can assist.

To send a Live Chat, click the Peer to Peer chat icon at the top right of the page and enter Xfinity Support in the "To" section of the chat.

I no longer actively support the Comcast Business Forum or work for Comcast.

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3 years ago

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user_248146

New Contributor

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1 Message

2 years ago

I'm having the same problem, with this message

host mx2h1.comcast.net[96.102.157.179] said: 421 4.1.0 [IP address] Throttled - try again later. Please see http://postmaster.comcast.net/smtp-error-codes.php#RL000001

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Comcast_Dena

Official Employee

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76 Messages

I do want to thank you so much for taking the time out of your day to reach out through our Forums Channel. I can tell you have not had the best experience and I assure you I am here to do everything I can to turn this around. We appreciate your signing up to be a part of the Comcast family, and I want to be sure we can get everything figured out for you with your service. Please send me a Direct Message with your name and service address so that I can fully dive into this for you! I will leave you instructions on how to initiate the message with us! I look forward to working with you soon!

- Click "Sign In" if necessary
- Click the "Direct Message" icon (upper right corner of this page)
- Click the "New message" (pencil and paper) icon
- Type "Xfinity Support" in the to line and select "Xfinity Support" from the drop-down list
- Type your message in the text area near the bottom of the window
- Press Enter to send your message

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2 years ago

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R

ROEBC

New Contributor

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2 Messages

2 years ago

we are getting

Reason: [{LED=421 4.2.0 40.107.95.126 Throttled - try again later. Please see https://postmaster.comcast.net/smtp-error-codes.php#RL000003};{MSG=};{FQDN=mx2a1.COMCAST.NET};{IP=96.103.145.164};{LRT=12/19/2022 4:07:38 PM}]. OutboundProxyTargetIP: 96.103.145.164. OutboundProxyTargetHostName: mx2a1.COMCAST.NET

for emails sent out to our distribution list members who are comcast subscribers.

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CC_Kimberly

Contributor

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18 Messages

Thank you for bringing this to our attention and reaching out to our Forums Channel. Have you had a chance to visit https://spa.xfinity.com/postmaster?faq=avoid-blocks-ipv6 to see if any of this could be the cause of receiving the postmaster errors?

I no longer work for Comcast.

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2 years ago

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ROEBC

New Contributor

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2 Messages

@Comcast_KimberlyL

Yes. None of our ips are blocked. We are also 100% Dmarc compliant with all our spf includes properly entered in our DNS. I'd love to carry this over to an email correspondence with comcast to ensure our emails are delivered properly. Thanks much

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2 years ago

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CC_Jess

Contributor

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7 Messages

Please send us a direct message with your full name, business name, full address, and last four digits of your account number or full phone number.

• Click "Sign In" if necessary

• Click the "Direct Messaging" icon in the top right corner

• Click the "New message" (pencil and paper) icon

• The "To:" line prompts you to "Type the name of a person". Instead, type "Comcast Business" there

• - As you are typing a drop-down list appears. Select "Comcast Business" from that list

• - An "Comcast Business" graphic replaces the "To:" line

• Type your message in the text area near the bottom of the window

• Press Enter to send it

I no longer work for Comcast.

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Reply

2 years ago

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