Thunderbird Community Forum

I was happily using TB 78.14.0 on Mac OS 10.9.5 and I switched to using TB 140.6 on Mac OS 12.7.4, and it's now unusably slow. I've tried: troubleshoot mode with add-ons off; compacting folders; removing and renewing msf files; emptying junk and trash. Is there anything else, or is this just a failure or incompatibility of the app? I can't see that there's any antivirus app that might be interfering. Can something go wrong when you export the files from one TB into another? I would be grateful for any suggestions. Tim

Why suddenly has Thunderbird stopped logging my messages that I filter manually even though I have logging enabled? It used to work just fine. It no longer logs ANY message filtering. I have not changed any settings. I depend on it especially to confirm that new filters I set are working properly. How can i fix this?

For some time the feature to use color in text has not worked. I deleted and re-installed Thunderbird but no change. I cannot change the font color when typing an email, and making changes in the settings has no effect, either.

I have my "signature" saved as an HTML in color, and it also will only display in black.

Any articles and solutions posted seem to be for people using Macs or some other kind of computer. I have Windows 11 for a Lenovo Idea Pad 5. Thank you in advance for any and all guidance you can offer.

Hello, Sometimes, when I select multiple emails to be deleted, the system only deletes one, and I have to manually delete each remaining message. I have emptied trash, but that doesn't solve the problem. rebooting the computer fixes the problem some times.

FYI - the messages go from displaying in bold to displaying as read messages; but them are still displayed. This is a major pain in the butt!!! What is the solution to fix this. I am using a Lenovo ThinkCenter desktop computer, running Windows 7

Jimmy

Hi, am not finding anything helpful in the support area, so hoping someone can help me solve. When a calendar reminder pops up, and I try to snooze or dismiss, I get this message:

Status Code: 2,147,500,037, null

Server Replied with 400 If you’re seeing this message after snoozing or dismissing a reminder and this is for a calendar you do not want to add or edit events for, you can mark this calendar as read-only to avoid such experience in future. To do so, get to the calendar properties by right-clicking on this calendar in the list in the calendar or task view.

Thing is, I do want to add and edit events, so I have no other options and the reminder keeps popping up every couple of minutes it seems. Any help resolving is appreciated. Thx!

I have been trying to move my emails from an old (win10) PC to a new Win11 PC for two days now and still having problems. Can you please help with any ideas to solve my difficulty?

I have used the instructions and video on this link to the letter. https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer

The old PC is running win 10 pro 64-bit - thunderbird is version 146.0.1 (64-bit) My current profile is 5.3GB

The new PC is running win 11 pro 64-bit - thunderbird is version 146.0.1 (64-bit)

I have used the exact method shown in the video to copy the thunderbird folder in the roaming folder on the new PC. (C:\Users\beeni\AppData\Roaming\Thunderbird)

and then copied the thunderbird folder in the local folder as the instructions below the video in the link as I am copying profiles from win 10 to win 11. (C:\Users\beeni\AppData\Local\Thunderbird)

My username is different on the two PC's - is this important?

I'm using IMAP for new emails so only concerned about copying the emails from the local folders on the new PC.

Is there something I'm missing, can check or a method to copy the emails from the local inbox folder sections at a time to keep a zip export below 2gb?

Thank you for reading and helping

Dave

Some inbox entries cannot be deleted. When deletion is attempted the body text is removed but the Subject and Correspondent remain in the Inbox and the message is marked as unread. This seems to be mainly with email originating from Outlook. Tried restarting Thunderbird but no change. Is there a setting that might do this?

A search showed that others have experienced this same error message, but as far as I can tell, they all were unable to access their email. These messages began appearing about a month ago. They pop up in Troubleshooting Mode. They did not in Windows Safe Mode. AVG and ZoneAlarm are not the culprits.

I successfully installed Thunderbird version 146.01 in November 2025 and successfully completed the connection to my email server Comcast.net. With all folders downloaded I proceeded to receive and send emails without any issues until around December 17 2025 when Thunderbird stopped receiving or sending emails. I performed all the steps listed without success, When I test the connection in settings I get the following: "Successfully established a secure connection to imap.comcast.net:995." Yet I get no emails

I see a Thunderbird update came in around December 17 2025, maybe a coincidence? Thank you Ed

I installed Thunderbird and Proton as per "Resist kit" Australia and New Zealand but have not been able to arrange for transfer of one Gmail account completely and process is stalled. I'm required to sign in with a password for this Gmail account but only to set it up again. Who can I speak with please?

Recently, I have experienced an erroneous browser launch, simply by clicking on the title of the message in the list pane. This problem seems to occur when clicking on emails from a particular UK supermarket (tesco.com) and the web page opened has a long and complicated URL, but the page contains only a single pixel which shows up as a white dot on a black background.

Obviously, it is likely that there is something strange about that source, but the problem doesn't occur if I click on the same email in a different email client (in this case Evolution).

I have tried various Settings as advised by web searches and also the solutions suggested in Thunderbird Help (Troubleshooting Mode and Troubleshooting Information).

I am running Thunderbird 140.5.0esr (64-bit) on Kubuntu Linux 24.04.

Hi, my name is Rob and I have been using Thunderbird now for 3 months. Love it. There is a nagging issue. I have 2 gmail accounts. They both show events in the calendar. However one of my accounts when showing a reminder for an event, will not allow me to "Dismiss" it. Only solution is to close the dialog window. It shows the organizer as "Unknown organizer...." The other account works just fine. Any help is appreciated. Happy new year. Thx

Win 11 and Thunderbird 140 not working and I have tried all the things I found on the internet and none of them work. I have tried cleaning my registry and deleted directories and uninstalled thunderbird re-started and it will still not work.

I guess I have to forget thunderbird. It is a shame.

Hi, I setup an ubuntu 24.04 and used the default flatpak installation of thunderbird- I believe 146- via the software app, so it took a default option. Worked a few hours, then suddenly one of the 3 email accounts on outlook365 blocked sending, no messages. I tried to use some Delete "Start-Cache" option from thunderbird, and then it was no longer able to to boot, and hung up everytime. I had to delete it completely, and the user profile was gone. Not sure if an issue of Ubuntu 24.04 or of the latest Thunderbird on flatpak..I also have no error logs left, those where also deleted with the deinstallation. Ubuntu should go a version back. I meanwhile found some installation pathes for an ".deb" file and hope that will be more smooth. (I work since many years on thunderbird on my PC & Mac with no such problems ever- so this is very new) best regards, Philipp Fonberg, redacted@gmx.ch

I'm having troubles with Thunderbird version 140.6.0esr(64-bits) on Ubuntu 25.10 (fully updated). It's installed as a snap.

The first problem is that I have a selected mail with an attachment, but nowhere in the mail itself I can see or find or open or download that attachment.

The second problem is that for the inbox and mail body I can't scroll. There are no scrollbars, and the mouse-wheel doesn't work.

Is it a problem with snap? With Ubuntu? Or with Thunderbird itself? Could if be a configuration problem (I've tried quite a lot of things already)?

Can any one help please?

I help my brother inlaw with his computer, he has diminished mental capabilities when operating his PC. He has deleted his email address and its associated folders from Thunderbird and I cannot restore them for him. This is the only email address he has and does not remember the original password that was used to add the email address to Thunderbird, some years ago.

Regular Thunderbird user. Lester, Auckland N.Z.

Recently, I needed to do a major upgrade to Fedora 43 so I did a full backup first for safety. After the upgrade, I needed to install Thunderbird to recover access to my email. For the first time in over 20 years, I had to re-enter the data for my various email accounts and now I find that my address book is gone. How can I locate the proper files in my backup and restore them while Thunderbird isn't running?

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.