Thunderbird Community Forum

I have a completely vanilla install of TB fully up to date as of this writing [it is version = 156.0.1 (aarch64) and I checked for updates], no extensions, no proxy, on a new OSX 27.0 (Golden Gate) computer and even when idling it is using substantial resources. The only thing even remotely non-basic is their is the Proton Mail Bridge to connect to Proton Mail for one of the linked email accounts, but that is its own little program with its own threads and takes almost no system resources even when sending or receiving mail (which is not happening currently.) Look at the attached screen shot.

In the screen shot I have left Thunderbird to idle for about an hour. No new mail in that time and other then clicking on or off the window to bring it to the fore I have not interacted with the program at all myself. Meanwhile Thunderbird and its Thunderbird GPU Helper are using substantial amounts of the CPU and GPU, have a combine total of 86 threads (more then any two other things running except the kernal tasks) and are hogging ram (not depicted).

Meanwhile among a few other applications (Apple Music, OfficeLibre, etc...) I also have Brave Browser opened in the background running with two windows and a total of 8 tabs wherein Brave is actively downloading GB of data from MEGA as well as performing other admittedly lighter tasks. Even when doing all this, Brave barely registers on computer resources compared to Thunderbird and Thunderbird GPU Helper when they are just idling.

Is this all proton mail's fault with the Proton Mail Bridge? If not is there anything I can do to quell the hunger for computer resources of this voracious beast of an email client that is TB and uses resources as if it were a video game even when idling?

It's very odd. Normally moving an email, say from the Inbox to the relevant year's archive, takes "no time at all".

Which is true for all the mailboxes shown on the attached screenshot, EXCEPT for the four at the bottom. Moving even one message from Inbox to Yiddish can take ten seconds or longer (with the dreaded "Not Responding" occasionally). Moving something in the opposite direction is also screwy, only from those four.

I had thought that it was because they're rather large. This first started when there were just Yiddish and MSW, and I split off most of the earlier years into the archives shown. To no avail.

It's only an annoyance, but I'm puzzled about how such a thing could happen.

Also very slow tagging or untagging a message just in those mailboxes.

Moderator Notes:

• need a performance profile https://support.mozilla.org/en-US/kb/profiling-thunderbird-performance

My Thunderbird connected to my gmail is running slow. Thunderbird is not running slow on my other (non-gmail) account. It takes 10-15 seconds for an e-mail (from gmail) to be deleted or moved within Thunderbird. I have tried "compacting folders" and "repairing folders" and that does not help. Please help!

For a few days I'm having trouble with Asana mails (notification mails informing me about replies, comments, etc).

Clicking on the mail to view it freezes Thunderbird for a good 5 seconds while one CPU core spins at 100%. This only happens with Asana mails (or at least I haven't found any other problematic senders).

I guess it's a problem with validation or parsing of the mail's HTML content. But I don't know how to debug this.

I can't pinpoint exactly when it started happening, but it was around the time I've switched to the [new snap release track](https://support.mozilla.org/en-US/kb/channel-choices-thunderbird-snap-and-flatpak#w_snap-channel-changes-in-2026). But since this happens with Snap and Flatpak I think the culprit may be the 153.0 update.

Things I've tried:

• Clearing cache and msf files.
• Troubleshooting mode with add-ons disabled.
• Reinstallation. Creating new profile + importing old data.
• Switching from Snap to Flatpak
• Switching Message Body display to Plan Text or Simple HTML.
• Disabling HW acceleration.
• Checking console for suspicious output.

Anything I can do to create handle the problem or collect information for a proper bug report?

I'm on a 15" MacBook Air M5 running and updated OS to Golden Gate 27.0 a couple of days ago. when I Open Thunderbird the emails are up but page is blank, just spinning pizza wheel. I've force quit Thunderbird and restarted and force quit and shut down several times but ends up with the same result... just the spinning wheel. Any suggestions ?

Since the latest update, the uploading of new emails from the server can take minutes to hours. I know the emails are on the server, because I can see them by logging onto my email client on my iPad. Why has Thunderbird suddenly become very frustrating to use? An example which just happened - I was required to enter a 6 digit code to be able to confirm my account before I could submit this question. I waited, and waited and waited to see this code in my Inbox. Finally I went to my iPad to get the code, so I could submit this question. It was there as I expected, but not in my Thunderbird Inbox for another 10 minutes. This is happening far too often, so I am contemplating finding another email program which is not so frustrating.

Hello everyone. Thanks for all your support.

A few weeks ago I started noticing a pop up window was occurring every (approx) 5 minutes in Thunderbird suggesting that I run a compact to save 992MB. I assumed this would stop happening after a few weeks and a few updates from Mozilla, but the problem has remained, so I'm coming here to ask about it.

Context: I'm on Windows 11. I have multiple email accounts that my Thunderbird reaches out to. At least one of the accounts is retired so reaching out to its historical server fails.

Reproducing: For me to reproduce it, I run the compact. Quit Thunderbird. Start Thunderbird. It reports 992MB can be freed. I let it compact. The main inbox disappears and reappears. I wait a few seconds and restart Thunderbird. It again tells me that it can save 992MB by running a compact.

What I've tried: I've tried repair on the inbox folder of the account I'm typically in. That didn't help. I have many other folders across many accounts and not tried to repair any other folders. I've searched the Mozilla help system.

Logs: It seems to me that a compact is probably failing but I don't know where to look for evidence of the failure.

Thunderbird freezes when downloading email only from transaction@notice.aliexpress.com

Environment: Windows 11 Pro, Surfshark VPN and Bitdefender Total Thunderbird 156.0 (64-bit), yahoo.ca POP3 account

The Symptoms: Thunderbird stopped downloading emails from my yahoo.ca account with the message "Downloading message 1 of xx" where xx was increasing from one day to the next.

What I Have Tried: I disabled the antivirus and VPN without any result. I searched on internet and I tried the following solution:

 - I deleted the file named global-messages-db.sqlite
 - I repaired and compacted all the folders

without any result. I entered the web interface in my yahoo.ca account and I saw that after the last message downloaded in Thunderbird there was a message from transaction@notice.aliexpress.com. I deleted the message from transaction@notice.aliexpress.com, restarted Thunderbird and it started downloading messages until the next email from transaction@notice.aliexpress.com. I repeated the procedure several times with the same results. Thunderbird downloads any message except messages from transaction@notice.aliexpress.com. For example the messages from promotion@aliexpress.com are downloaded without problems.

I installed Thunderbird 156.0 (64-bit) on another computer I have, using the same environment, with the same result.

Any insights or guidance would be greatly appreciated!

I'm running Thunderbird 156.0 on Windows 11 with ten IMAP accounts (Gmail, Outlook.com and Zoho) plus one Exchange account served by the Owl add-on, and until recently about 30 GB of mail held locally. On starting Thunderbird, folders are destroyed and re-created empty. It happens often, but not every time. The summary files are deleted, and in some cases the whole folder directory goes with its mbox message store inside it. The folders then come back in the folder pane holding nothing, and Thunderbird downloads all the mail again over several hours, re-indexing as it goes. When a folder directory has been re-created, it appears on disk with a numeric suffix, so one of my folders now lives at COMPLIANCE-1.sbd with an abandoned COMPLIANCE-2.sbd sitting beside it. Column layouts and favourite-folder flags are lost at the same time, because they live in the summary files. It happens on ordinary restarts, rather than after Windows updates or sleep.

Those orphaned directories have let me date three separate occurrences: 18 August 2025, 19 February 2026 and 19 September 2026 — those being the occasions that happened to leave orphaned directories behind. Most leave no trace, because the folder refills and the evidence is overwritten. Each has the same signature. A folder directory is created, and roughly five minutes later a summary file of about 1,200 to 1,500 bytes, which is an empty summary, is written into it. In the two older cases it was never touched again. In one event eleven summary files across two folder trees were written with an identical timestamp to the second, so it appears to be a single operation across a set of folders rather than something that walks through them one at a time. One of the destroyed folders left its mbox stores behind, orphaned with no summary file, while another was deleted whole with 50 MB of mail inside it, so there seem to be two different outcomes in the same event. Bitdefender is running, but its quarantine holds nothing from the September event, and there are no Thunderbird entries in the Windows event log for that period.

The part that may be useful is that I have reproduced it. On 19 September I renamed folderCache.json aside with Thunderbird closed and restarted. Eight minutes later folders were destroyed. The twelve I could identify were all children of INBOX, across two different mail providers, though other folders elsewhere were emptied in the same minute. The Exchange account served by the Owl add-on was untouched. At the moment of destruction the Activity Manager showed "[NONEXISTENT] Invalid folder: INBOX^Practice Filing (Failure)" on the Gmail account, where the correct hierarchy delimiter is a forward slash rather than a caret. My folderCache.json is 5.2 MB with about 13,000 entries, of which roughly 1,200 point at summary files that no longer exist and 9,600 sit under an obsolete lowercase profile path from the 129 to 139 version window. I would rather not delete it again given what happened, so I'm looking for any idea of what triggers this on an ordinary restart, and whether there is anything I can set that would stop Thunderbird discarding local folders when it decides they are missing.

I am going in circles with this. If I build a new profile, is there any point bringing the old configuration across, or would that just reimport whatever is wrong? I assume the address books and filter files are safe and that folderCache.json, prefs.js and the unified-folders directories are not, but I do not know whether the problem lives in the profile at all, or in how Thunderbird handles an account set this size.

Any ideas?

I am running Thunderbird 140.9.1esr on openSUSE Tumbleweed.

For a long time now, Thunderbird often runs at high CPU (80-100% of one core), for several minutes at a time (5-10 minutes). This seems to happen many times every day, with no apparent cause from my end. (I just got back from Lunch, and the fan on my laptop was going crazy because of the high CPU.)

What can we do to identify and fix this issue?

I have thunderbird for many years and now giving me trouble with my email that I get from comcast not letting email to come up says not responding and when it comes up and check the mail and then lower it to taskbar and their is a second copy which I lower it also also please help this is all has started recently and need help badly. If you need more information please let me know

I reported this to you by last Friday but I have received no response so far. After reporting to you, I tried all possible trouble tests and checks, then took following steps. 1 - I deleted my copy of Thunderbird from my PC 2 - I loaded a new copy of Thunderbird - all went well 3 - But situation remains, the program opens, reacts very slowly to commands but I can not get into any functions. Thunderbird does not show any emails, nor can I read older emails stored on my computer 4 - I ask you kindly for speedy help, my email function is fully down. Yours - Jarl Jaatinen - Finland

Noticed in LM, the last couple Tbird versions, the context menu doesn't close, when click anywhere on active window, away from the context menu. Happens if R click a message in thread pane, or pretty much anywhere else that R clicking opens a menu.

• Only* hitting Esc key closes it.

Could be a profile issue? (but isn't due to theme used in Tbird - tested several, incl. native w/ Tb package).

Normally, opening a context menu, then L clicking anywhere inside the active window, closes the context menu (how it works in Firefox).

Also, opening a context in Tbird (if don't close it), switch to another app, the Tbird context menu shows on top that app.

We are facing issues with Thunderbird mail application.

Incoming emails are not being received in Thunderbird. Thunderbird is running very slowly and frequently becomes unresponsive. Sending and receiving emails is taking a long time. We have already restarted the application and system, but the issue still persists.

Kindly check the mail server settings and Thunderbird configuration from your end and advise on the necessary action to resolve this issue as soon as possible.

Your prompt support will be highly appreciated.

In the last month or 2, when I delete an email it does not show in the trash folder. I can wait from 5 minutes to even the next time I reboot my puter to finally see it it trash. Sometimes it sends it to the all mail or important folder instead of trash. And if I delete from there, it still takes tons of time to end up in the trash folder...if it even gets there. This seems to be getting worse by the day. I have clicked repair folder, no change, I have cleared Thunderbird's cache, no change. It's also now taking way too much time to load an email that contains a picture. This happens with at least 3 of these gmails. I'm at a loss here and extremely frustrated and about to change these gmails from imap to pop. win10 and TB is up to date. But it doesn't compact folders as much as it used to either. Any help appreciated

I don't know where to start. Ever since the update to version 154 I've been having one problem after another: switch from Comcast to Yahoo causes problems with THunderbird, slow indexing, arbitrary folders showing up in different email addresses (confuses my account with my wife's' some of that may be problems dealing with gmail issues), lost email folders after attempted repairs. Three months ago there were none of these problems. I have not yet tried switching back to the last updated version of 153, but 154 does seem to have many more problems. I've run troubleshooting.

I am not a computer expert and there is only so much time I can devote to this, but even computer repair services I've called are at a loss and very pessimistic about the ability to repair things. In all the years (over a decade) my wife and I have used Thunderbird, there have never been as many problems as have surfaced in the last two months. Maybe the best that can be done is to hope that updated versions will gradually fix these issues. I will say that my Macbook Air (M2 chip) has far more problems than my iMac (M1 chip). I have checked and rechecked all server settings (smtp and imap). Although more cumbersome, things perhaps work better if I just stick to webmail options.

All of a sudden I have to open the program twice for it to run. First time the screen opens but it is just blank and says it is not responding. So I close it and then open it again and it is fine. Anyone know why this is happening?