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heidilaf77
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56 Messages

Sunday, March 8th, 2026 9:04 PM

Xfinity Is Blocking Emails from my Gmail Account

Hello. Xfinity has suddenly started blocking any emails sent from my Gmail address -- including to my own two Comcast email addresses (and to my friend's Comcast email). I am receiving this bounce-back message:

451 4.2.0 Throttled - https://postmaster.comcast.net/smtp-error-codes.php#RL000010

Can you please help me get my Gmail address unblocked? It is a work Gmail address and I regularly send messages to my own personal Comcast email accounts. They should not be considered spam, although they may include one or two links (to webpages and videos). Nothing out of the ordinary though and nothing that should get blacklisted. 

Thank you! 

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Updated 

3 hours ago

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XfinityThomasD

Official Employee

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1.7K Messages

2 days ago

 

heidilaf77 I'm sorry to hear that you're having trouble receiving emails from your Gmail address. For email blocks or blacklisting, I would recommend contacting our Customer Security Assurance Team, as they specialize in assisting with any security email or website issues. They can be contacted by phone at 1-888-565-4329 and are available every day from 8:00 am - 12:00 am EST.

 

2

heidilaf77

Contributor

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56 Messages

Thank you! I will give this number a try. 

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1 day ago

0

XfinityMatthew

Official Employee

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1.6K Messages

You're welcome. Let us know if you have any issues connecting with them. 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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1 day ago

fwunder

Frequent Visitor

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10 Messages

1 day ago

I am having the exact same problem:

451 4.2.0 Throttled - https://postmaster.comcast.net/smtp-error-codes.php#RL000010

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0

Zeroneight

New Poster

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2 Messages

17 hours ago

I am also having this problem.  It just started yesterday.

2

0

XfinityNatalie

Official Employee

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622 Messages

Hey there, Zeroneight! Thanks for reaching out to our XFINITY Community forum. We are sorry to hear that you are experiencing this issue as well. Does this issue occur when you are trying to send large attachments? 

 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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17 hours ago

0

user_4r8lwi

Visitor

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3 Messages

I am also having this issue with a Comcast email address. 

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6 hours ago

0

user_4r8lwi

Visitor

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3 Messages

6 hours ago

I am also having this issue without sending any attachments at all.   This needs to be fixed as this is for business to business!  

3

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XfinityAmira

Official Employee

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4.7K Messages

Hi user_4r8lwi! Thanks for reaching out on our Xfinity Forum letting us know you're also running into this issue with your Comcast email. Please know my team is here to help! Just to confirm, you're having issues with both sending and receiving to Gmail accounts from your Comcast email? 

 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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3 hours ago

0

user_q37cd3

Visitor

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1 Message

@XfinityAmira​ - I'm not the above user.. But the problem isnt with sending or email from my comcast email.  Its sending from my Gmail TO  ANY comcast email account.

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3 hours ago

0

XfinityMartyR

Official Employee

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3K Messages

 

user_q37cd3 If you're getting the same RL000020 error back, I would recommend reaching out to our Customer Security Assurance Team (CSA). 
 
 

 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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Reply

3 hours ago

0

user_m3xqsp

Visitor

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1 Message

3 hours ago

Having the same problem for the last 4 days. 

My Gmail account is unable to send to Comcast accounts.  I am getting the "delivery incomplete" notice and the Comcast email users confirmed they are not receiving emails from my Gmail account.   

I am Xfinity customer with Xfinity internet service, but using Gmail email account. 

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