rambo19's profile

Frequent Visitor

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11 Messages

08/28/2026 6:00 PM

Outgoing Emails Won't SEND On My Thunderbird Client

After years of using Thunderbird to receive and send emails, all of the sudden my emails will not send.  When I try I get this message:

Sending of the message failed. An error occurred while sending mail: Outgoing server (SMTP) error. The server responded: resomta-a2p-647141.sys.comcast.net resomta-a2p-647141.sys.comcast.net ESMTP server not available (396356/151.247.189.217).

I don't know what this message means since I test the server and it says it's okay: 

Description: Comcast Server Type: SMTP Outgoing Server Server Name: smtp.comcast.net Port: 465 User Name: [EDITED: Personal Information] Authentication method: OAuth2 Connection Security: SSL/TLS

When I test the server, I get this message: Successfully established a secure connection to smtp.comcast.net:465.  This tells me the port is good.  I don't know what the ESMTP is.  What's wrong??

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Official Employee

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2.6K Messages

8 days ago

HI there, @rambo19. Thanks fore reaching out to us here on the Community Forum. Sorry to hear you're having trouble. Do you use any other devices with your Comcast email besides the one you're working on? This error usually occurs when there is another device or profile trying to connect that has an incorrect password. 

Frequent Visitor

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11 Messages

No other devices.  Desktop computer only since day one many years ago.

Official Employee

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2.4K Messages

@rambo19  Have you attempted to reset the password for your Xfinity email account and then log back in on the mail client?

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 as Best Answer.tick

Frequent Visitor

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11 Messages

Official Employee

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1K Messages

What is the make/model of the desktop computer you are using, rambo19?

(edited)

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 as Best Answer.tick

Frequent Visitor

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11 Messages

The desk top computer was a local custom built computer May 2025 with Windows 11 Home, AMD R7 CPU, 32GB, 1TB NVME.  

Contributor

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372 Messages

1 hour ago

Make sure Thunderbird is up to date.
Current version is 155.0

If you want to install another email client try eM Client.

I use it as a backup.

https://www.emclient.com/

They have a free version

Here is a link to their documentation (online manual).

https://www.emclient.com/webdocumentation/en/10.3/eMClient/Default.htm#Getting%20Started/Getting%20Started.htm%3FTocPath%3DGetting%2520Started%7C_____1

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