Thunderbird Community Forum

I'm in the process of cleaning up Thunderbird e-mail before moving to a new computer. I started with 11,593 e-mails in my Inbox and 7,799 e-mails in my Sent folder. I'm now down to 7,634 in my Inbox and 4,965 in my Sent folder. I've allocated 2 weeks for this process and found that it's taking me about 3 hours per day to meet my daily goals. I'm finding that I'm spending at LEAST half the time responding to "Empty-Trash/Compact-folders" requests. There are times I can delete 50 e-mails at a time without getting a request. Other times I will try to delete ten e-mails and get the request. With the old version of Thunderbird I could literally delete hundreds of e-mails at a time. Can you help? Russ Bukwa Yardley, PA ps. I have intentionally given you specific numbers. Based on my software- and test-engineering experience, I speculate you need to create a stress test to solve this nagging problem.

In the past, as Thunderbird was spell checking (triggered by pushing Send), it would highlight the words it questioned. For the last few weeks, maybe longer, it still spell checks, but the words it stops at are no longer highlighted. So I don’t know where in the body of the email the issue occurs. Without seeing the context around the potential misspelled word, I can’t tell if I should accept the suggested correction, or push Ignore.

I’ve attached a screen shot of Thunderbird stopping at “interlibrary” but there is no indication at that word in the body of the email.

When I tried a simpler example - one sentence with a misspelling - the misspelling was given a red underline. And occasionally, a questioned word would be highlighted. But it use to work reliably ALL the time.

What can I do to bring back highlighting the questionable word? I didn’t realize how much more useful it made the spell checking.

I previously successfully imported my configuration from Thunderbird desktop to my mobile app by scanning a QR code, and it worked perfectly. However, I recently had to reinstall my computer's operating system, which resulted in losing all my Thunderbird data. Now I'm trying to export the configuration from my mobile Thunderbird app back to the desktop version, but the export process generates a file with a .k9s extension. My question is: How can I import this .k9s file into my desktop Thunderbird installation? Any guidance on this would be greatly appreciated. Thank you!

We are trying to create an out-of-office response email and have found an issue. When creating the filter to respond with, the "Reply with template" option under "Perform these actions" is missing. We have checked the usual reasons why, but we cannot find what the problem is. We are using an Imap account. We have the 139.0.2 version of thunderbird, and we have set up the template necessary for the response without any issues. What could be the solution?

I can access addons.thunderbird.net with Firefox without any problems or being asked to "verify you are human by completing the action below.", yet when I try to access it from Thunderbird's add-ons manager, I am asked to complete the captcha, which after about 30 seconds of "Verifying you are human. This may take a few seconds." goes back to "verify you are human by completing the action below." I tried troubleshoot mode to no avail, I am not using a VPN or anything like that.

Hello, I have a problem with one email account. Grouping does not affect it. It does not group... Everything was OK but I changed the POP server address to MAIL for a moment and then back to POP. Since then the account has not grouped. I want to have all the mailboxes "received" together. What could be the reason that this one account does not group and it used to group?

Mozilla's documentation on IMAP Synchronization Mozilla's documentation on IMAP Synchronization indicates

"Non-synchronized messages are still accessible within Thunderbird. The only difference is that rather than downloading the entire message, only the message "headers" are downloaded. (Message headers contain information like the sender, recipient(s), subject, etc - everything except the body of the message.) The message body is not downloaded until you click on the message in the message list"

Under what settings (e.g. Sync messages checked or unchecked) does this behavior apply?

Thanks.

I have 4 email accounts setup in Thunderbird. When I turn my laptop on and open the program all the email accounts automatically expand(open to show their folders). I then have scroll up thru all the accounts and folders to get back to the top account. If I don't shut down or reboot they will stay closed or go back to what state they were in when last closed. If I reboot or turn on pc again they all expand.

I shut down and boot many times a day when moving around the office or on calls. So it kinda annoys me and slows me down. I cant seem to find a setting that fixes this if it is even possible. I want them to stay closed till I open them.

When I receive some special html formatted email e.g. from ticket system like Zendesk they look like this: https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/images/2025-06-17-01-06-32-c4ca42.png

When I want to reply to the text stays at the blue colored background and the text would be hard to read and it looks ugly: https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/images/2025-06-17-01-06-37-c81e72.png

Unfortunately I can't change background color to blank or white in Tunderbird 139.0.2. In menu of reply window "Page colors and Background", "Use custom colors", "Background" I can set to #ffffff of course, click apply and ok, but that doesn't change it: https://assets-prod.sumo.prod.webservices.mozgcp.net/media/uploads/images/2025-06-17-01-06-42-eccbc8.png

I suppose it relies to the html formatting of the received email because on starting to write a complete new email it works. But that's very annoying that Thunderbird doesn't manage to change background colors on already formatted html body. Is this a bug or only poor source code and the programmer didn't have much motivation to write and robust code which could gather all html emails?

Could you check with this test email to test and reproduce? https://limewire.com/d/pqbEk#1idjNje6b2

Thanks a lot! I'd be very happy about your help.

I am struggling trying to get a consistent format in Thunderbird. First of all let me say that I am happy with the default use of paragraph style and if I want to have occasional single spacing I can use shift-enter instead of enter. Most queries on formatting seem to be about getting single spacing all the time. That is not my issue. That means that if I compose an email from scratch everything is just the way I want it, using the default settings. The problem arises when I reply to an email. The settings then seem to be ignored. For instance the line spacing can be fixed to single spacing whether I select paragraph or body text and no matter what I do I can't get it to follow the default behaviour. Also, I noticed that the font goes to "sans-serifArial" instead of the usual "Variable Width". In fact if I try to select "Variable Width" in the Format menu it is just ignored. How do I get the default composition settings when I reply to an incoming email?

With some of the messages I receive and with film sites such as Netflix and HBO Max, the screen becomes too large to access the control column on the right, a necessary manuever as the scroll arrow has suddenly lost its ability to scroll when that column is no longer seen. What do I need to do to rectify this?

How do I enable the display of the number of selected feeds? I have all toolbars enabled, but as I select feeds in the navigation panel, I don't see the changing number anywhere. The context menu of selected feeds only has the following items:

1. Options
2. Open in New Tab
3. Open in New Window
4. Delete
5. Move To >
6. Copy To >
7. Compact
8. Mark Folder as Read

Hi! I'm trying to set Thunderbird as the operating system default under Win 11. I tried to follow Mozilla's instructions: 1. Open the Settings application by pressing and releasing the Windows Start button, then clicking the gear icon. 2. Click the Apps icon, then click Default Apps in the list. 3. Click the icon under the heading Email to show your choices. 4. Select Thunderbird. The trouble is that at n. 3 there is no choice. There is only 'OutlookAccounts' and this item cannot be deleted or replaced. Can you help? All the best, Robifiori

Hello,

I am using the latest stable version of Thunderbird on Windows to read FTN (Fidonet) echo conferences that are relayed via NNTP (specifically, through Eternal September).

While the message bodies are usually readable, I have persistent issues with:

Unreadable or corrupted Subject headers

Author names displayed with wrong characters or encoding artifacts

Some headers showing as raw MIME encoding (e.g., =?KOI8-R?B?...) or complete gibberish

I suspect the issue is related to legacy Cyrillic encodings such as KOI8-R or CP866, which are still common in FTN systems. It seems Thunderbird does not properly decode these in NNTP headers.

I’ve attached a screenshot illustrating the problem.

My questions:

Is there any way to force Thunderbird to decode NNTP headers using a specific charset (like KOI8-R)?

Are there any config settings, hidden preferences (about:config), or recommended add-ons to fix this behavior?

Is there an open bug or known limitation related to non-UTF8 header decoding in NNTP messages?

I do not face this issue when reading standard UTF-8 NNTP groups or emails — only FTN-derived groups.

Thank you in advance for any advice. I’m happy to help with diagnostics or testing.

Best regards, Vladislav