Thunderbird Community Forum

After Windows installed an update in the middle of the night I can't open Thunderbird and I've tried uninstalling it and reinstalling with success.

It says: Thunderbird is already running, but is not responding. The old Thunderbird process must be closed to open a new window.

I've rebooted the PC, shut down the PC, ended the task and still nothing. It seem that Thunderbird didn't shut down correctly and the system still thinks that it's open and running. Anyone know how I can fix this issue?

Thanks,

Gregg

At startup of Thunderbird, get error related to Outlook which I do not use. Get message - "UserHasNoMailboxandNoLicenseAssignedError"

How do I get rid of this error, has been present since last esr release and expected it to go away with new release - did not. Do I have to reinstall Thunderbird to clear.

I have an account that I am not aware of having requested. The address is the same as the original account and the inbox appears to also be the same. It does state POP3 after the address. I want to remove this account. How can I do that?

When I tried to delete the account all the emails before today on the POP3 address and the original address disappeared. Is it possible to get the emails back or the recent ones?

I want to switch back from the Thunderbird Release channel to the ESR channel but I do not understand the steps. Please help me with the exact, easiest steps. I am running Win 11.

Hello:

My Windows Thunderbird has become unresponsive, taking forever to connect to my various accounts. I suspect the problem is with my GMail account--which is not my primary account--is causing the problem, but I am unable to un-sync GMail's All Mail folder.

I was able to get into troubleshooting mode, but TB was still unresponsive.

I have copied the profile in question to my Linux machine, with TB V140.4.0esr, to try to repair the profile, but the problem is recurring there as well.

Is there a way to manually edit the profile file(s) to remove the GMail account from Thunderbird?

Any insights would be much appreciated.

Thanks

DrP

Running Thunderbird 140.5.0esr

This has been happening for a few weeks now somewhat randomly. The folders under Mail for one of my accounts keep moving around and are not in alphabetical order anymore. Most folders are OK, but a few either jump to the top of bottom of the list. I can manually drag them back, only for different folders to do it the next time.

The folders in questions are 2 levels down from Mail.

I'm dealing with a properly updated 'bird: 140.5.0 (32-bit) running on an equally updated Windows 10 desktop. First thing this morning, out of nowhere, I started getting an "unable to write the email to the mailbox..." message when sending, thus I could send but not save. And then I realized I wasn't receiving either, on all three accounts in my Thunderbird. I stopped everything and focused on trying to fix this. It's been an all-day, losing effort. So far.

I tried the various quick checks and fixes recommended here and there: I'm running the program as an administrator. I restarted the program. I rebooted the computer. I think I have enough disk space, but to be sure I deleted some bloat from possibly overly large files. I compacted, even though the program is configured to do that regularly. I temporarily disabled my antivirus program. I went into my webmail and deleted all messages that have arrived since my Thunderbird stopped receiving, in case one of them was corrupted. And probably some other attempts as well. Nothing has helped.

And now a second, even worse issue has fallen from the sky. Thunderbird opens. The folder list is where it always has been. The number of unopened messages in each folder is there in boldface, as always, but...the folders are all blank and I get the dreaded popup: "unable to open the summary file...." Have I lost my years' worth of carefully curated emails?

I've tried folder repair. I've deleted parent.lock. Etc. Nothing. Nothing. Nothing.

I will be super-grateful for any wisdom sent my way.

Hi, I have thunderbird connected to a number of client corporate Office 365 systems (5 in total). The teams option works fine for 4 of them and is quite usable for chat but one of them responds that the browser is an unsupported version. I use Ubuntu 24.04 and have thunderbird and firefox installed from deb files (and the repos) so both are the current/release versions and overall everything works well so I don't believe there is a systemic issue. All connections to the clients' exchange systems are through the owl plugin. With the one client, as soon as you try to connect to their teams site, the 'Hmmm, your browser isn't supported' page comes up. As I manage that client's office platform, I know I've not made any changes to the back-end settings nor have I done so or had to do so on any of my other clients platforms so I don't think there is anything unusual about the Office 365 side (but am willing to be proved wrong). If I try logging in to the problematic teams site using firefox it works perfectly so I don't believe it is firefox being an issue. I have deleted and re-added the account. Has anyone else seen this and got it sorted, and if so how please? Many thanks, Scott...

Hello, I recently cleaned up my mail account and deleted obsolete folders on one device. The folder has been deleted on the server, but Thunderbird on another computer still shows the folder. In the subscribe menu the folder is not shown. But when I try to delete it it throws an error "The current command did not succeed. The mail server for account <account name> responded: [NONEXISTENT] unknown source folder.". The error makes sense since the folder has been deleted on the server. Is there a way to tell Thunderbird to just remove this folder?

Thanks in advance!

Hello,

I created an event in the Thunderbird calendar, inluded 30 e-mail addresses of which only 19 calendar invites were sent. It sent the invites in the order of the recipient list and just stopped at number 19..

What could be the problem here?

Thunderbird version 140.5.0esr on Ubuntu.

Forwarded emails contain no signature, either above or below the forwarded email body.

No means exists in settings to specify that a signature should be in forwarded emails.

Thunderbird resists configuration for included signatures specified in the configuration editor.

Is there a reason that settings, such as columns, layout, ordering, folder colours, etc. are not retained in the msf itself?

I have to use multiple machines, so tend to have an archive that I share across them as the primary storage of emails. However, nothing is retained between machines which is a bit annoying when trying to colour code for easy visual cues. So it seems clear that this information is currently stored in the local profile, even though the archive data is a filesystem.

Hi, I am using Thunderbird on my Android phone and PC. When I send emails from my Android phone, the emails are sent but a copy is not stored in the "SENT" folder of my phone. This feature used to work in the past, but now it doesn't anymore.

How can I resolve this? Thank you.

Today filtering of new emails fails for all folders. The message is "The message could not be filtered to folder <folder> because adding a message to it failed. Verify that the folder is displaying properly or try to repair it from the folder properties."

This is new. No problem filtering message a few days ago.

Windows 10 laptop PC.

Lots of free space on my local drive where Thunderbird is installed.

Where are these folders stored? I looked in C:\Program Files\Mozilla Thunderbird but I do not see any such folders there. I looked in C:\ProgramData\Mozilla but nothing there either.

Thank you.

I had knee replacement surgery on 10/10/2025 and was unable to access my PC to download email. When I was able to access my PC(physically unable to get to the PC until12/7/2025) email had stopped downloading after 10/27.2025 and many of the ones downloaded were multiple copies of the same text. I decided to just highlight a large group of email and just trash them unread. I have now trashed 5000+ emails and the system will stil not display any after 10.27/2025. I am at my whits end, I am a 78 year old retired non-software engineer and really need some help. This is my primary email account and really need to read what's current.