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can't send email from Thunderbird now but could before

  • 6 replies
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  • Last reply by kjperkins2

kjperkins2
kjperkins2
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Recently I have been unable to send email from Thunderbird although I can still receive email in Thunderbird. I get the following error message: 

 "The message could not be sent because the connection to Outgoing server (SMTP) smtp.comcast.net was lost in the middle of the transaction.Try again."

However, I can send email when I log into my Comcast email account from a web browser (Firefox). Therefore, when I called Comcast, they insisted the problem in Thunderbird or some other app. I doubt that, however, because a local tech support company took my PC and did the following to troubleshoot the problem:

- They tried using an email client other than Thunderbird and still could not send email and got the same error. - They deleted my email account in Thunderbird, uninstalled Thunderbird, and then reinstalled Thunderbird and added my email account but was unable to send email and got the same error message. - They installed Thunderbird on a different PC and added my email account but was unable to send email and got the same error message. - They checked the third-party setting for accessing Comcast email and it was set correctly as Security->Third party access.


Here's my configuration. I've also attached screen shot of my Thunderbird settings. • My mail provider: Comcast • ISP: Comcast • Firewall version and antivirus software: Kapersky Total Security version 21.3.10.391 • OS: Windows 10 Home version 22H2 • Thunderbird 115.2.3

Recently I have been unable to send email from Thunderbird although I can still receive email in Thunderbird. I get the following error message: "The message could not be sent because the connection to Outgoing server (SMTP) smtp.comcast.net was lost in the middle of the transaction.Try again." However, I can send email when I log into my Comcast email account from a web browser (Firefox). Therefore, when I called Comcast, they insisted the problem in Thunderbird or some other app. I doubt that, however, because a local tech support company took my PC and did the following to troubleshoot the problem: - They tried using an email client other than Thunderbird and still could not send email and got the same error. - They deleted my email account in Thunderbird, uninstalled Thunderbird, and then reinstalled Thunderbird and added my email account but was unable to send email and got the same error message. - They installed Thunderbird on a different PC and added my email account but was unable to send email and got the same error message. - They checked the third-party setting for accessing Comcast email and it was set correctly as Security->Third party access. Here's my configuration. I've also attached screen shot of my Thunderbird settings. • My mail provider: Comcast • ISP: Comcast • Firewall version and antivirus software: Kapersky Total Security version 21.3.10.391 • OS: Windows 10 Home version 22H2 • Thunderbird 115.2.3
Attached screenshots

All Replies (6)

sfhowes
sfhowes
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You have two accounts and two smtp servers. Is the rog-mar account sending on an smtp that has the rog-mar User Name, and is the mar-rog account sending on an smtp that has the mar-rog User Name?

https://support.mozilla.org/en-US/questions/1350593

kjperkins2
kjperkins2 Question owner
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Yes, both accounts are sending on an SMTP server that's associated with the correct user name. Nothing in the configuration has been changed lately; it's all the same configuration as when I was able to send email previously.

sfhowes
sfhowes
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Do a test with Windows running in safe mode to see if any startup apps, especially Kaspersky, are interfering.

kjperkins2
kjperkins2 Question owner
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I tried running a test with Windows in safe mode + networking but was still unable to send email from Thunderbird. I got the same error message indicating the connection to the outgoing SMTP server (smtp.comcast.net) was lost in the middle of the transaction.

sfhowes
sfhowes
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Try changing the outgoing port to 587 with STARTTLS security, which is a suggested option on the Xfinity site.

kjperkins2
kjperkins2 Question owner
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I changed the port and security as you suggested but still could not send email and received the same error message indicating the connection to the outgoing SMTP server (smtp.comcast.net) was lost in the middle of the transaction.