Thunderbird Community Forum

Thunderbird has always had a problem with filtering all incoming mail to the correct folders. Sometimes it does it correctly and sometimes it doesn't. But this morning it is dumping all my incoming mail into a folder that isn't the Incoming mail folder.

How do I get it to put the incoming mail in the Incoming folder?

As of September 3, 2026 all my new emails are going into a random folder instead of the inbox. This is also happening on my wife's PC plus and we are not getting the emails to our iPhones until we get out of Thunderbird. What has changed? This has not happened before.

Hallo zusammen. Ich kann seid etwa 2 Wochen keine Nachrichten mehr in meinen Lokalen Ordner archivieren. Habe schon sehr viel ausprobiert: - Papierkorb geleert - Archiv komprimiert - Lokalen Ordner neu aufgebaut (.msf-Dateien entfernt) - komplett neues leeres Archiv an einem neuen Speicherort erstellt. Es kommt immer die selbe Meldung: Die Nachricht konnte nicht in den Ordner "Archiv/2026/2026-09 in Lokale Ordner" verschoben oder kopiert werden, da das Schreiben in den Ordner fehlgeschlagen ist. Um Speicherplatz frei zu machen, wählen Sie aus dem Menü "Datei" zuerst "Papierkorb leeren" und dann "Alle Ordner des Kontos komprimieren". Versuchen Sie es dann nochmals. Hat jemand eine Idee wie ich das beheben kann?

Hello,

My internet provider is RCN. For the past couple of months, I’ve occasionally been getting the message, “Connection to server imap.rcn.com timed out.” As a result, I’m unable to receive emails via Thunderbird.

All my settings are correct. Usually, the problem resolves itself within 24 hours, but sometimes, like this time, it lasts longer.

Any suggestions? Best, Magda

I have "Allow remote content in messages" turned off. However I receive many messages for which I wish to allow it for that message. I do so and it works fine.

What I would like to be able to do is to have TB learn the message senders for whom I have allowed remote content so I don't have to click it every time. Is this a feature that is available that I am missing, or is it just not possible?

If not possible, please advise as I will submit for an enhancement.

I have Thunderbird 155.0 installed and also, TBSync + Google-4-TbSync to synchronise contacts between TB and Google.

However, I have just realised it hasn't been working for several months and TBSync is no longer compatible.

Are there other tools/techniques available to sync the contacts with Google?

I have been using Thunderbird successfully on Windows for years now, as my email client for a PlusNet email account in the UK. In May 2026 Thunderbird suddenly disappeared, as if it had been uninstalled, but I have no idea why. I managed to reinstall it and rediscovered the server details needed to reconnect to my account and fortunately had a slightly old back up (from Nov 2025) of previously saved emails. This has worked OK now for about a month.

Today the same thing has happened again - The Thunderbird icon on my desktop does not connect to anything and has just turned into a white "blank page" icon.

I may be able to get the account back by doing the same tedious process again, but I am concerned that this may keep happening and I don't know why.

This is a work laptop running Windows 11 so its possible I suppose that some sort of security software may be doing this without notifying me?? I am using Thunderbird to access a personal (ie not work) email account so maybe my work systems don't like that? As mentioned, it has worked fine for years so I dont know where the problem lies but it is worrying and annoying.

PlusNet last year transferred all email accounts to another UK provider (Greenby) but that has worked OK and I cannot see how that would affect email client software.

BJ

Starting today (September 3), ALL of my received emails are being put into the Spam folder instead of the Inbox.

FYI, I have been running Thunderbird (TB) for years and have not recently set up any new filters.

I'm currently running Thunderbird 64-bit version 155.0 under Windows 11 Home version 25H2. I am also running Bitdefender Total Security, but I have turned off its Antispam function, both under my usual Standard User account and the Admin account.

I have tried:

1. Going into TB Settings|Privacy & Security|Spam and clicking on "Reset Training Data." 2. After closing TB, I deleted the training.dat file in my TB profile folder and restarted TB. 3. Right-clicked on my Inbox and Spam folders and clicked on "Repair Folder." 4. Exited TB, copied my profile folder to an external HD, uninstalled TB and reinstalled TB after downloading from the official download site. 5. Rebooted my PC.

None of these approaches has worked to solve my problem.

Thanks for any help you can give.

I have been using Thunderbird for years. Suddenly, a couple of days ago, the sent and trash folders no longer show the emails in them. When I use Roundcube online, these files show up there as normal.

I have done considerable research online to solve this problem to no avail. Using AI, they suggest a number of things that I have tried, without solving the problem. Apparently, this is somewhat common. I finally got to deleting the send.msf and trash .msf. This did nothing to solve the problem.

This is very frustrating. What can I try next? I am using Win 11 and Version 152.

Carl

Was on version 115, had this problem. Updated to version 155, same problem. One of the email accounts I set up on Thunderbird is redacted1@lake48.net, registered with 123-Reg. However, this is a forwarding address and has no email server, which is why I am getting the error now.

Messages addressed to redacted1@lake48.net are forwarded to redacted2@lake48.net, which does have a server, My system was to download from there and use a rule to divert the incoming message to my redacted1@lake48.net Inbox. This has worked OK until now. Thunderbird gives me this error right at the start and then does not respond, so I cannot get in to investigate account settings, and cannot access emails in other accounts such as gmail. 123-Reg has today changed its system, assuring me I don't need to change anything. Clearly I do, but I can't get in to change it.

What should I do to resolve this? I have no other access to my emails.

Notification requests I would like Thunderbird to 1) notify me that I have received new email(s) even before I have opened Thunderbird. Partly by changing the icon on the taskbar and partly by playing a sound. And 2) also retrieve the emails that are there automatically when I open Thunderbird. Is that possible? How do I do that? K.r. /hans peter

After fixing the view problem of my email in Thunderbird (thanks for the F8 tip!), my email stopped downloading. I have no "prompt for password" checked. There isn't a primary password checked. I've confirmed the pop outgoing email is correct with the email provider (google). I can get into it without any issues and see my emails there.

I've re-entered the password for the pop outgoing email to no avail.

After your upgrade I was unable to send messages. The incoming I was able to fix but the outgoing I could not fix. I have included the email message sent to me and I have included a picture of the outgoing STMP,

Somewhat frustrating ... just after installing and setting up CardBook for Thunderbird on all devices... it automatically deactivated and "disappeared". CardBook no longer is compatible with Thunderbird.

Hope there will be an update soon that allows to keep all the settings...

Thanks.

Thunderbird won’t open because it wants a Primary Password which I have never had to do. I went on another computer (the one that I am currently using) and generated a password for Mozilla. I tried that but it still would not open. I have restarted the computer 3 times. When it asks for the pass word, I have entered the new one for Mozilla with no success. I have tried the one for the main opening of the computer with no success. When I close the small window that asks for the Primary Password, the spinning beach ball of death shows up and eventually (maybe 10 minutes) it has to be forced to quit.

Since the last (v155) update, TBird started putting all incoming email into one subfolder under my main inbox. I have several message filters that sort incoming mail into various folders. When I disabled the message filter associated with the folder in question, the email started coming into my inbox folder again. The message filter connected to that folder has not been changed in a while, and is a "match any of the following" rule with a number of specific from/contains/[text] entries. When I examined the filter closely, I found two rules where the [text] field was blank, which apparently was causing the problem, but as I said, I haven't changed the filter in a while - what recent change might have caused this? (Either adding empty fields or else considering [blank] to be equivalent to [any].)

Most other email clients I've used have had a way to manually "expunge" a mailbox, i.e. delete the messages which are marked for deletion. This includes Thunderbird on a machine at home (I'm traveling right now).

On this laptop I'm using Thunderbird 102.12.0 on macOS 26.6.2. All of my mailboxes use IMAP. Thunderbird is using Maildir for local storage on this laptop, and I believe the same is true on the machine at home (also macOS 26.6.x, not sure of the exact Thunderbird version), but I won't be able to verify this until I get home tomorrow evening.

On both machines, when I delete a message, the message list shows that message with a line through it, corresponding to the IMAP "marked for deletion" flag. The same is true on the other email clients I've used over the years.

On the machine at home , when I right-click on an account's "Inbox" folder, there is a "Compress folder" option which expunges the deleted messages from the mailbox. This option is not present in Thunderbird on this laptop.

So my questions are ...

• Is the menu item I'm talking about, only present when the account uses MBOX for local storage, and maybe I missed a step when I created the account on the machine at home? (If so, I know how to fix that when I get home.)
• Every email client I remember using, all the way back to the original `pine` in the mid-1990's, has had an "expunge" command of some kind. Does Thunderbird really not have a way to manually expunge a mailbox? If so, this seems like a fundamental oversight on the part of the Mozilla developers.
• Or is there a way to do it, and my old eyes just aren't seeing it on the menus? (which is entirely possible)

Thanks.

(Side question, totally unrelated) ... why does the text entry control I'm typing this message into, have its own markup language instead of using standard Markdown? (And yes I am, at least in part, being old and gumbly here ... you kids get off my lawn!)

MY second email account (droulston@btinternet.com) stopped working 3 days back (it has been OK for many years). I tried uninstalling and reinstalling but my password was not accepted.