Thunderbird Community Forum

Good afternoon,

We are experiencing the following issue.

I work as a Technical Support Engineer at a large company in Russia. All of our branches use Thunderbird as their email client.

Approximately three weeks ago, we started receiving reports from users that their email was no longer working.

After investigating the issue and trying to identify the root cause, we have not been able to find a permanent solution. We have already tried the following:

1. Completely clearing the cache, rebuilding the mailbox while preserving emails, and allowing Thunderbird to re-download all messages. 2. Changing the `mail.server.default.mime_parts_on_demand` and `mail.imap.mime_parts_on_demand` configuration settings to `false`, clearing the Trash folder, and restarting Thunderbird. (This only provided a temporary fix.) 3. Reinstalling Thunderbird and creating a fresh client installation. 4. Using the **Repair Folder** and **Compact Folder** options for every mailbox folder. 5. Several other troubleshooting methods found online, none of which resolved the issue.

According to multiple users from different departments who are not connected to one another, they all describe the same behavior:

Thunderbird stops working for about half a day. Then it starts working normally for approximately 15–30 minutes, after which it stops working again for another several hours. During these periods, no new emails are downloaded, regardless of the size or content of the messages.

When checking the mailbox size in Exchange, it reports:

• 3.56 GB used. The quota is unlimited.

However, on the local computer, the Thunderbird profile folder (`Thunderbird > Profiles`) occupies nearly 9 GB. If we calculate the size of all mailbox folders within Thunderbird itself, the total is approximately 6 GB.

Does anyone have any suggestions on what else we can try?

Has anyone experienced a similar issue or found a solution?

At this point, our employees are unable to work effectively because email is a critical part of their daily workflow, and we have been unable to identify a permanent fix.

I'm getting off a Verizon phone account and want to export my contacts before I do. I use an (old!) iPhone 8 so I can't export using their Verizon Cloud app because my operating system is too old. Is there a way to import into Thunderbird using a USB cord? Or is there a recommended non-evil app that could allow me to do the same with my phone contacts?

Hi all!

I'm having some issues with using Thunderbird with my Outlook account. From a fresh Thunderbird profile, I can sign in to the account, and get the Microsoft authentication popup. Afterwards, Thunderbird works until I close and reopen the app. After that, I get authentication failures when fetching mails.

This is only with IMAP. POP works, but I'd like to sort my emails with server-side rules.

My system is freshly updated (Thunderbird 152.0 on CachyOS 7.1.3-2).

If anyone could help me, I'd be much obliged!

Cheers!

Hello,

I'm hoping someone can help me recover a local task calendar.

Environment Thunderbird 152.0.1 (aarch64) macOS Local Thunderbird calendar (not Google, Exchange, or CalDAV) What happened

Several months ago I deleted a local calendar because I believed I was no longer using it. Unfortunately, that calendar contained all of my Thunderbird tasks.

After deleting the calendar:

the local calendar disappeared from Thunderbird all of my tasks disappeared I have not created any new local tasks since then

What I have recovered

I have an older copy of my Thunderbird profile from before the deletion.

From that profile I have:

calendar-data/local.sqlite prefs.js

I inspected the SQLite database and confirmed that it contains 394 tasks.

The task records appear intact, including task metadata such as:

titles categories completion information recurrence tables alarm/snooze tables related Thunderbird calendar metadata

All of the recovered tasks belong to the same calendar ID:

8420c0c3-6b20-436c-a39b-d4183d2665e1

Current profile

My current profile contains only my two iCloud CalDAV calendars.

The deleted local calendar no longer appears in prefs.js.

Because of that, the task database appears to be orphaned.

What I have already tried Restoring the old local.sqlite Creating a new local calendar Exporting the tasks to ICS and importing them

Thunderbird reports:

"No importable items found in the file."

My question

Since the task records still exist in the original local.sqlite, is there a supported way to:

recreate the missing local calendar definition so Thunderbird recognizes the existing tasks, or migrate the orphaned tasks into a new local calendar?

If necessary, I'm happy to provide:

the recovered local.sqlite the current prefs.js any additional profile files

My goal is simply to recover the 394 tasks into my current Thunderbird profile without losing any data.

Thank you for any guidance.

I've completed all the required information when trying to add an account to Thunderbird. The Account Hub finds my email address at Posteo and loads the configuration found out the provider. I then add my password, which I know to be correct as I've only just created it. But Thunderbird keeps telling me there is an "authentication error". I'm at a loss to know what the error is.

I have changed the website hosting company from my previous one to scalahosting.com, which in turn appears to be using grok.viawebhost.com as their mailserver.

I was a user of Eudora 7.1 for many years, but because of this change of hosting company, the Eudora email program would not connect to the Scalahosting site.

Thus I was forced to change to Thunderbird. After reading several webposting on this matter, I found and uploaded V17.0.9 and proceeded to convert the Eudora email, filters and addresses to the Thunderbird format.

This was not an easy task, and even with Google's AI assistance, I had to restart several times, but as of today - mid-Jun I have now completed the task of cleaning up all the email, installing the correct headers, etc that allows the Thunderbird program to open and correctly display all of those email without any problems.

I further cleaned up and corrected all of the Eudora filters to the TB format and now have those filters in TB to be able to be installed and correctly are accepted by the TB program.

Like wise with the contact addressee that were in the Eudora NNdbase.nnt file were cleaned up and correctly installed in the TB program.

However, the current status of the TB program is that it does not seem to be able to connect to the Scala Webhosting email site at grok.viawebhost.com. Enclosed is a pic of the supposed correct set up for the STMP at Port 465.

The other Port info from Scala is: POP3 - 995 (SSL) IMAP - 993 (SSL)

But I am not sure what else I need to do to correctly set up this older version so that I can start the collection process of the most recent emails sitting in the mailserver.

Further, it was suggested that I need to update the TB V17.0.9 to the most recent V151 by following the below sequence of updates:

According to Mozilla Support Documentation, this is the exact, official sequence to migrate safely from a legacy version:

Step 1: Run V24.8.0 (32-bit) (This updates the raw database schema out of V17. Upgrades the raw Mbox structures.)

Step 2: Run V45.8.0 (32-bit) (Stabilizes the folder indexing schema.)

Step 3: Run V52.9.1 (32-bit) (The final 32-bit staging version.60.9.1 (64-bit). Migrates the architecture to 64-bit processing.)

Step 4: Run V60.9.1 (This is the critical gatekeeper version required to unlock modern automatic profile conversion).

Step 5: Run V78.14 (This shifts the mail indexing formats).

Step 6: Run V102.15.1 (This modernizes the folder structure configurations).

Step 7: Final jump to V151.0.1 (Updates the background engine to current web standards).

I am looking any advice or suggestions from the Community that can assist me in completing this conversion to the TB program and get it fully functional so I can connect to the Scala Hosting mailserver.

Many thanks in advance for your assistance.

/s/ James T Saint

When I'm in Calendar, I see a certain time interval, depending on screen size. In the first example below, it goes from 07:00 to 21:00. When I toggle between Calendar and Email tabs (using shift+tab or by mouse-clicking) and back to Calendar, the time interval now shows 06:15-20:15. (second image) If I toggle once more, it starts at 05:15, and so on, it goes back one hour after each toggle, until it reaches 00:15. This is very annoying because I have to constantly toggle between Email and Calendar, so the Calendar is more and more shifted and I have to move it manually to keep working. I haven't seen this bug described before. Do other people experience it? Any solutions?

Thanks, Franck

Today i moved mails between folders. The move was successful, as confirmed by the webmailer. However Thunderbird stopped displaying these messages. Instead i got several popups, that the server is not available.

I have 2 issues with that:

First: Popups are disruptive. Especially when they block interaction with Thunderbird. Especially when using a tiling windowmanager(sway). Especially when there are multiple, which need to be closed in a specific order, because interaction is blocked by the newer popups.

How can i block these popups? Disable sync is not a reasonable option.

Second: Why did thunderbird not display the moved messages? Is it a bug? Or a config issue?

Until recently I could click and hold and drag a message from my inbox to any other folder that I had on the left of the screen. It just recently stopped doing this. Any help would be greatly appreciated. I am running Thunderbird 140.12.1esr (64-bit) on a windows 11 pc.

I'm running Thunderbird Ver 152.0.1 with Windows 11. I have things set up so that I just need a single click to open a program, folder or file.

This also was the case until just recently with Thunderbird. I could open new messages with just a single click. For some reason this has changed to me needing to double click to open new messages.

I don't know why and cannot find any method of changing the software back to single click operation. It is only affecting Thunderbird all the Windows operations still operate with one click.

Can you advise me on how to reset the Thunderbird software to single click operation.

Many thanks. Alan Tierney

I am experiencing an issue where clicking links inside Thunderbird emails forces Microsoft Edge to launch a completely brand new window with a blank profile (no extensions, default settings). It does not open as a new tab in my active window.

My environment details:

• OS: Windows 11 (Version 25H2) • Default Browser: Microsoft Edge (Only one profile exists under edge://settings/profiles, no Workspaces used). • Thunderbird version: Latest stable release.

When Thunderbird passes the HTTP/HTTPS link to Windows, Edge seems to ignore the standard "Default" user data directory profile and launches a temporary or guest-like profile container instead.

Is this a known bug in how Thunderbird handles external URI handlers, or is it an Edge registry/default app assignment issue? Any help or workaround config settings would be appreciated. Thank you!

Thunderbird shows email messages from the wrong account. The messages show properly in Yahoo website and on other computers using Thunderbird. Concurrent with this new issue, I now get message: Sending of the message failed. An error occurred while sending mail. The mail server responded: "Request failed: Mailbox unavailable. Please verify that your email address is correct in your account settings and try again."

I have verified the settings. Searching for help with Thunderbird, I see references to index files getting corrupt. However, I struggle with the correction procedures. When I right click on the bolded email address, "Properties" is not an option on the drop down menu. I cannot find a "Fix folders" button.

BTW, I did contribute December 17, 2025, it seems like a pretty good way to say "thank you!" Jim