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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 had logged this issue in early 2025 but it has never been resolved and still exists.

I received a reply today, Tuesday 7th July, from Wayne Mery, who said "If you are still having problems when using a newer version, please post a new question and we'll take a new look at it.". as the original post has been archived.

So, here are the details:

"I am currently running Thunderbird 152.0.1 (64-bit) and I don't get an automatic prompt for updates and haven't been getting them since I updated to Supernova and now Nebula.

I have the settings set to Check for updates, but let me choose whether to install them, which is the setting I have always had and I used to get automatic prompts for updates with a window opening to show the details of the update as I get in Firefox.

Can someone tell me how to get these automatic updates back."

I have attached a screenshot of the original version.

Thanks.

Windooze 11. TBird 152.0 installed on June 20th. Now it seems like TBird is not displaying HTML emails properly. They are displayed but not at the beginning. The first line is sometimes just the bottom half of a sentence in the email (if that makes sense). I can't scroll back to the beginning. If I go to outlook and display the same email it displays fine.

Did something change in 152.0 to cause this?

Thanks, Ed Mazurek

Login to server smtp-mail.outlook.com with username XXXXXX@outlook.com failed.

I am having this error I have tried logging back in, can download mail but not send any. Any ideas? Thank you

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.

Over the last week or so, I have received an enormous amount of scam, but no matter how many times I "train" the filter, it doesn't work.

I have just received another 3 from this site: mid:02guhjkj6-ABMcSHN6Or-JiC-000000@eu-central-1.amazonses.com, which claim to be from Madasafish Security>security@qi9adgongzenElptrum.de

I have tried on several occasions to follow the manual instructions how to deal with the spam, but I find it so log-winded that my non-techie brain, which is not wired for these kind of things, gets tired and I give up. If anyone has a more intuitive approach how to deal with this, I would be very appreciative. I have marked sites multiple times as spam, but the spam control ignores me!

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, I have two accounts in my Thunderbird. They are Gmail (regular gmail account) and CFCC (an institutional account). The CFCC shows up in my Unified Folder list but the Gmail does not. Is that normal? The main Inbox is showing all incoming emails from both accounts so no performance issues, just wondering how to get rid of the CFCC (if that's possible) to eliminate clutter. Thank you. GES

There is (of all things!) almost too much information to process about using Firefox's email, messaging, and security options. It seems there is no longer a dedicated email application, and I cannot disentangle what I need to do to either move completely from gmail or mask my gmail account somehow through a maze of layers.

I have attached a screenshot of the retention settings for the Gmail All Mail folder. This folder contains emails that have a date nine years ago. Can you tell me if I did something wrong in the retention settings?

I thought earlier today it was using the retention settings but I just checked and it is not.

Hello.I just want to let you know,that somehow the client what i uzsdeing is forget to make undread massages to read when i takea look at them.When i double clivck on them they open a diffferent page and then they get read status.What could cause this?

I have been using Thunderbird on my PC for years and when I got my last PC, I found a article to help me move my files. I am now looking for instructions on how to move my Thunderbird files from the PC to the Mac so I can continue using it as I have been.

Having tried all solutions I can find on the web nothing works. Computer is new windows 10 with only edge and thunderbird.. My other established computer windows 11, established thunderbird with yahoo and Plusnet working ok but outlook keeps failing despite test connections working and message from Microsoft saying thunderbird has accessed my outlook account. The problem is outgoings. Incoming gine

Since I upgraded to 152.0.1, some s/mime encrypted messages do not display. This happens for both old and new messages. Moreover, for these messages, the flag of "new" stays active even after I click on it, suggesting that thunderbird did not "read" the message. The encryption is done by posteo.de automatically for any email that arrives to me. Even the simplest email just written "test" fails systematically when I send it to myself, but some messages sent from others also fail to display. I have installed the extended support version 140.12.1esr (aarch64) to check, and the emails display fine with it.

Anyone with a similar issue or idea of the problem, which I guess might be a bug? Thanks, cassio.

First this is an installation on a PC. My local folders for Thunderbird are stored on an external drive. I rarely need to go to this drive, but on occasion I store a temp file for use on another PC. I was doing just that when I noticed a large number of SBD folders and MSF files there. For general description, on that drive I have local folder for Thunderbird. I also have folders A through Z which have nothing to do with Thunderbird, just other misc. folders for temp use. Thunderbird has gone through and created a second folder for each folder A through Z and an MSF file for each folder. Each one of these SBD folders has a sub SBD folder for each file that is in the original folder and an MSF file. Is it safe to delete all of these folders since they are not any part of emails. Why and how to prevent this from happening to stop clutter in my primary folder. Thank you for any advice and help.

After many years of using Thunderbird I am now considering ditching it. I am continually getting the Authorisation Failure message when trying to open Thunderbird. Why does this keep happening? It does not happen on my Android devices, just on Windows 11. I have tried deleting all three gmail accounts and re entering them. All is fine until I close down Thunderbird and then open it again. I run Norton 360 and have tried taking off Norton email security, but that didn't work. Any ideas, please?

I have a Trash Bin which had Subfolders under it.. Not thinking I emptied the Trash Bin and the SUBFOLDERS DELETED as well. Is there any way I can RECOVER THE SUBFOLDERS and Emails in them. I am 74 years of age and not very Computer or Email savvy so please keep it simple. Thanks Joe

Hello community,

at my place of work no one can send or receive mail anmore using Thunderbird. The problem suddenly appeared last monday. No changes regarding the network or settings in Thunderbird happened prior to this.

Here's what I tried so far and things I can rule out:

• same problem appears on all devices (desktop and laptop PCs) in our office
• our work mail server is online and working, I can access everything using the webmail-interface in the office network
• new installation of Thunderbird without any profiles and fresh account confguration doesn't solve the problem
• I can connect to our mail provider and send and receive mail when using my home network or my personal phone hotspot
• I can connect to my private mail provider using Thunderbird while in the office network
• troubleshooting mode doesn't solve the issue
• renewing the internet connection on our router temporarily/once allowed some devices to receive mail
• pinging the mail server (mailserver.[workdomain].de, no specific port) via command line was successful while Thunderbird was unable to connect to the mail accounts

IMAP-Log returns the following error codes:

• D/IMAP URL failed with code 0x804b000e
• D/IMAP URL failed with code 0x804b001e

I would be glad if somebody could help me out. If you need any more details I'll provide them. Thanks in advance!