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I cannot send emails from my laptop running Windows 10 Pro, using Thunderbird 102.9.1 on

Frustrated_Plus48Frustrated_Plus48 Posts: 2 Spectator
edited May 10 in Email Apr 13, 2023

I use Thunderbird 102.9.1 (32-bit). On afternoon of March 30, 2023, I lost the ability to "Send" messages. When I hit "send", the small box comes up, the blue bar goes all the way across the screen...and, freezes there. I have conferred with my source ISP at "" (company name is Spectrum) in Michigan (we are Snowbirds) and with the local ISP several times and they seem to not know what the problem is. The ISP has not been able to get my laptop back up with sending.

When I try to "send" I also eventually get this error message:

"An error occurred while sending mail: Outgoing server (SMTP) error. The server responded: cmsmtp blocked. Please see

for more information. AUP#Out-1130."

That error code says: "The IP address you’re trying to connect from has an issue with the Domain Name System. Spectrum requires a full circle DNS for emails to be allowed through. Verify the IP you’re connecting from, and check the IP address to ensure a reverse DNS entry exists for the IP. If the IP address is a Spectrum-provided email address, contact us."

My firewall is Windows Security that comes with Windows 10 Pro; my Anti-Virus software is Malwarebytes Premium 4.5.25; Operating System is Windows 10 Pro v. 22H2; and, my Email Client is Thunderbird 102.9.1 (32-bit).

Any help out there?

Accepted Answers


  • Frustrated_Plus48Frustrated_Plus48 Posts: 2 Spectator
    Apr 14, 2023

    Can you suggest a course of action for me to follow to re-establish the ability to "send" from my email client?

    We are Michigan based snowbirds spending Winter months in Florida, hence, Comcast is our local ISP. Any suggestions on solutions?

  • HT_GreenfieldHT_Greenfield Posts: 334 Contributor
    edited April 15 Apr 15, 2023

    No sweat. Visit the byzantines’ support forum at and search on the phrase PTR and then change the sort order of the results to most recent and then peruse some of those conversations and see how not-too-uncommon of a problem it’s been with them for the past couple of years and how rather effectively they now seem to be able to acknowledge and fix the problem for their subscribers right there.

This discussion has been closed.