Start Windows in safe mode with networking enabled.

Does the problem go away?

Hello christ1, Thanks for your reply. I do not have problems with my laptop that would justify starting it in safe mode. Networking is working perfectly. Wifi is working, Firefox is working, Total Commander is working and is accessing other devices in the LAN, FTP is working, communication with Android is working, VPN is working, thus doing things like starting windows in safe mode, reinstalling windows, formatting disks, buying a new laptop, etc, are not the logical way to solve this problem. Thunderbird is working, it is receiving messages but, suddenly, after installing the mentioned update, it is showing the described odd behavior. Thus the problem is related to Thunderbird. I could remove Thunderbird and then reinstall it again (preferably the previous version if I could) , but I would have to take care to preserve the emails that are there, and later, after the new installation I would have to associate them with the new fresh install. It would take a lot of time for an experiment. I prefer to wait for acknowledgement of this odd behavior and for a workaround.

Please try Windows safe mode with networking enabled.

Hello christ1, Just to be sure about the quality of your advice: I have restarted in safe mode with networking on, started Thunderbird and tried to send a test email to another email address. The message I got when I pressed the send button was:

"An error occurred sending mail: SMTP server smtp.gmail.com is unknown. The server may be incorrectly configured. Please verify that your SMTP server settings are correct and try again."

As I had already predicted, not the way to go.

Thanks for your time anyway.

TB24.6 works for me on Windows 7 at work and Windows 8 and LMDE at home. Therefore I conclude it is not broken and you have a local problem.

By all means downgrade to the previous version. Or upgrade the other computer to see if it is consistent.

If 24.6 were definitively broken, do you not think this site and mozillazine et al would be swamped by complaints?

Your firewall may not recognise 24.6 hence the advice given to run in Windows safe mode.

The "server unknown" message hints at a DNS problem.

Hello Zenos, Thanks for your reply. <quote> The "server unknown" message hints at a DNS problem. <unquote> Do you remember reading in my first post that I have accessed smtp.gmail.com using PING and using TELNET? Well, how could DNS be a problem if I accessed that domain (google.com) name (instead of using an IP address) using those tools?

If your firewall is specifically blocking the thunderbird executable, then other routes/programs/clients may still work. But we would hope this would be overcome by using Windows' safe mode where your firewall is disabled. But not all firewalls go away when asked to.

You have mentioned, in different places, both google.com and gmail.com. Both don't work in Thunderbird?

But as I say, TB 24.6.0 works for me at various locations and on various OSes (two flavours of Windows and a Linux distro, LMDE.) I can't see that TB is definitively broken.

Old versions here: https://ftp.mozilla.org/pub/mozilla.org/thunderbird/releases/

…so you can freely upgrade and downgrade. Go back to TB24.5.0 if you really feel it wasn't broken.

In short, we don't know enough to replicate your problem anywhere else.

Hello Zenos, Thanks for your reply. I like it more than previous ones. Concerning : "You have mentioned, in different places, both google.com and gmail.com. Both don't work in Thunderbird? ". This was my error writing the message here. I meant "gmail.com" not "google.com", my apologies.

I have posted the original message also on the mozillazine.org forum (http://forums.mozillazine.org/viewtopic.php?f=39&t=2843573&e=0), and another victim of the same problem showed up, with the same connection time out problem. I am not alone in this.

I like your reply more, because you are explaining why the advice was given to start windows in safe mode: to exclude connection blocking by the firewall as a possible cause. In make case, as I am not a beginner in these matters, it would have been a better suggestion to ask to disable the firewall and to explain why. My firewall is the stock windows firewall of Win 8.1. Checked the logging and I saw no blockings. Everything there had the status "action"=allow. Also, the firewall was set to notify me when the firewall blocks any connection, and that did not happen with TB. Thus the firewall was not the cause of the problem.

I followed the suggestion of DanRaish in the mozillazine.org forum and downloaded the EnumProcess.exe tool. After download, as a matter of precaution I checked it using virustotal.com, before I executed it. Then I tried again to send an email from Thunderbird while the tool was active and to my complete surprise the email went thru. Go figure ! Exited the EnumProcess.exe tool tested again and Thunderbird now keeps working.

This is one of the mysteries one encounters from time to time. Thunderbird does not send messages for 2 days and then it starts sending them again, without any change in the settings of TB, without any changes in the firewall, without any windows updates being applied in the meantime.

In any case, the problem for now seems solved, but TB gave me a psychological blow. My confidence in the product got harmed.

Thanks for your input.

ok, so the time to live on your dodgy DNS data expired and your dns cache was refreshed is how I would see this.