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user_8ji45d
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Thursday, April 30th, 2026 11:45 AM

Can't check email from AT&T network

This has happened before and it is now happening again.   I cannot check email from an AT&T network.   Email works fine from a Verizon or Comcast network.   Device does not matter... does not work from iPhone or  PC.

iPhone gives the message:  The mail server imap.comcast.net is not responding.  Verify that you entered the correct account info in mail settings.   Server code 'ALERT' server message:  Temporarily blacklisted IP Address, try again later"

Settings are fine... it works from other networks.  Client does not matter.   It fails on all clients when using AT&T networks.  I can access the email through the Xfinity website just not through Outlook/Thunderbird/Apple Email clients etc... 

It has been week or so now.   

This is a recurring problem.   It seems to align when a router gets a new 'temporary' IP from AT&T residential fiber service.   There is nothing nefarious going on... just the occasional new IP from rebooted systems and the fact that it only seems to happen with AT&T networks... 





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19 days ago

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XfinityGabriel

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19 days ago

 

user_8ji45d Hi there! Thanks for reaching out. I can understand the inconvenience caused by not being able to check email from an AT&T network. You’re not alone. The key clue is the error “Temporarily blacklisted IP Address” and the fact that it only happens on AT&T networks, while the same accounts work fine on Verizon/Comcast and via webmail. This usually shows up after AT&T assigns a new residential IP. Nothing malicious on your end. Some AT&T IP ranges just get flagged. There’s no local fix; it typically requires removing the IP block. As a workaround, people often note that using a VPN or switching networks works immediately, which confirms it’s IP‑based. How long have you experienced this error?

 

 

Here are some key troubleshooting steps to try:

  • Request New IP from AT&T: Reboot your AT&T Fiber Gateway/Router to force it to request a new IP address from the DHCP pool, which may resolve the blacklisting.
  • Use a VPN: Connect through a VPN to change your IP address, allowing you to circumvent the temporary IP ban.
  • Utilize Webmail: Since you can access the Xfinity web portal, continue using it as a temporary solution.

To resolve an IP conflict, another option is to release and renew your IP address. Here are the steps for Windows 10:

  1. Click **Start** and type **CMD** in the search box, then click **OK**.
  2. In the Command Prompt, type **ipconfig/release** and press **Enter**.
  3. Next, type **ipconfig/renew** and press **Enter**.


This process will usually help remove any IP block by refreshing your IP address. Additionally, ensure your computer is set to use DHCP and not a static IP address.

 

 

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