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I use folder icon colors for various purposes. I prefer my color selection "menu" to look like the first included image, after I define and Add to Custom Colors.

After a restart of TB, my custom color choices go away. I believe the color choices should survive and be permanent until changed by the user. Please advise, thank you.

I had 12 important draft messages in my "drafts" subfolder of one of my e-mail accounts. This e-mail account is a work e-mail based in Outlook, and I use Thunderbird to download those e-mails to my laptop, and to compose e-mails. The 12 messages in that Thunderbird folder suddenly disappeared, and have also disappeared from my "drafts" folder in Outlook. (The Thunderbird and the Outlook accounts are linked.) I did not change any settings. This has never happened before. Those missing e-mails do not appear in the "deleted items" folder in Thunderbird or in Outlook. It is extremely frustrating and is causing problems at work.

Oddly, my Thunderbird listing of folders still shows the number "12" next to the name of the "drafts" folder. But, there are no e-mails visible in that folder. All my other Thunderbird folders for this e-mail and for my other e-mail are working properly. Please help.

It appears how TB handles IMAP connections for outlook email accounts no longer works - OAuth2 connection flow broken, and this is likely due to stricter changes made on Microsoft's backend that is impacting connections going forward.

I have multiple email accounts configured and recently, I have been bombarded by login pop up - likely related to the OAuth2 authentic process.

Whilst I was able to circumvent the authentication process - i.e. not completing the flow process entirely as it expected, newly created outlook accounts appear to reveal two things:

1] There has been a recent change to the authentication process - i.e. the telling sign.

2] There is a now deeper issue when trying to connect outlook email accounts. It seems the reason why circumvention was possible with existing accounts was because they have already passed the OAuth2 process correctly - correct tokens exist. Since this won't be the case for new outlook accounts - no OAuth IMAP access token created, above error is given.

It seems the likely cause is because Thunderbird holds or requests a token that does not contain the correct IMAP audience/scope combination, and Exchange rejects it during SASL XOAUTH2 bind.

For your information, I am using the latest versions and able to configure Apple Mail client - which uses Exchange protocol (not IMAP), without issues.

Hi!

I'm losing my mind by the fact that you can't hold to scroll or click to toggle scroll with MMB in Thunderbird, instead it opens a new tab which is completely useless to me since I share inbox and mail reader in one screen.

Is there any way to fix or change this?

If not I'd really like to request this as an option or feature.

More often than it should happen, when I try to reply to a message, TB opens a screen that is surrounded by a thick white line and I can't type in the field. Why? How to I fix it?

Hi

When Thunderbird is started maximized it overlap taskbar if is set to hide and taskbar won't show until Thunderbird is minimized and maximized. Another way is to press the Win key two times. Then the hided taskbar can be shown/use. The same thing happens to Firefox. Only when is first started. Then if Firefox is minimized and maximized, press Win key two times, press F11 two times then the hided taskbar show/hide normal.

It is a setting that can be changed to start Thunderbird and Firefox in full screen and do not overlap hided taskbar?

Возникает ошибка:

Ошибка отправления сообщения. Сообщение не может быть отправлено, так как не удалось установить соединение с Сервером исходящей почты (SMTP) «smtp.gmail.com». Сервер может быть недоступен или отказывать в соединении по SMTP. Убедитесь, что указали корректные параметры Сервера исходящей почты (SMTP) и попробуйте снова.

In our organization we have moved from an on-premise mail server to M365. We've also added our new EWS-based accounts to Thunderbird. Since there are a large number of users with a significant amount of older mails they want to have access to, they have been asking how they could upload them to EWS now.

From the looks of it, using TB one can either drag and drop messages from the local folders to EWS. Would message copy/move from the local folders be faster if the EWS account was setup over IMAP, instead of over EWS? If so, we could setup another account corresponding to the same EWS identity, but over IMAP, just for the purposes of transferring messages faster.

Thanks in advance for any information provided.

Edition Windows 10 IoT Enterprise LTSC Version 21H2 Installiert am ‎18.‎09.‎2025 Betriebssystembuild 19044.6937

Thunderbird Version 148.0 von Feb 2026

bis zum 5.3.2026 funktoinierte TB einwandfrei, aber seit gestern kann ich keine Mails mehr versenden, folgende Fehlermeldung wird angezeigt siehe Bild Hochgeladen. Gestern wurde die IP 18.195.155.157 angezeigt, heute 3.70.126.251

Empfangen von E-Mails hat funktioniert nur beim Senden oder Weiterleiten kommt die Fehlermeldung.

es Spielt auch keine Rolle von welchem Konto ich Mails verfasse, ob T-online,Web oder Agenturserver

Benutze den Acount auch auf einem Laptop mit W11, dort funktioniert alles,

Die SMTP Einstellungen hab ich überprüft, Laptop und diesem PC sind identisch (Hatte ja auch keine Änderung in diesem Bereich durchgeführt)

I already have two Exchange email accounts using Exquilla that were created in earlier T-bird versions, they work in the latest version as well. I am trying to add a third exchange account, I enter the email and password do auto discover and get the following error; Invalid or missing password: password does not exist in the directory for this user. Trace ID: b2766d8c-6b02-4879-ab77-e30177281600 Correlation ID: 220ef2bd-c4b2-42a9-9414-d4f7bc0dae35 Timestamp: 2026-03-06 02:43:34Z

An Autodiscover site was found, but we could not find a usable entry. This is probably because your server does not support Exchange Web Services (EWS). If your server does not support EWS, then ExQuilla will not work for you. If you believe this to be in error, try manually entering the EWS URL.

I know the message is wrong since I have two accounts that function. I have gone through the manual configuration as indicated online and still have no success just says "URL test failed". I was hoping this latest version would have another way to be able to enter information to get around the failure. Any guidance is greatly appreciated.

I have been using Mozilla Thunderbird for decades and they have even contributed a small amount of money to Thunderbird periodically. Just within the last two or three days all of a sudden I have been unable to send emails with my phone. I receive emails, but I do not send them.

So I opened up a laptop where I did not have Thunderbird and set it up properly through Spectrum using the incoming and outgoing servers as mail.twc.com. and yes, just like on my phone. I continue to receive new emails, but even with the laptop I was unable to send an email.

I received the message"send message error sending a message failed. The message could not be sent because the connection to outgoing server smtp mail.twc.com was lost in the middle of the transaction. Try again."

I contacted Spectrum twice and both times they had me try to send a message through their Web server spectrum.net and that message did go through. Of course then their response is that this has to be a problem with the third-party app meaning Mozilla Thunderbird, and they can’t help with that at all. I sure would appreciate some help because I hate to walk away from Thunderbird as well as change my email address after all of these decades.

Hi everyone! Why do I get an error when I try to download messages - "Failed to save message. Check the spelling of the file name, wait a while, and try again"

And the most annoying thing is that after this error, downloading other letters stops and you have to manually search for that very letter, although there may be thousands of them... Please fix this!

Hello! The other day everything worked as usual, and I shut down the computer for the night. The next morning, Thunderbird immediately crashed/shut down when starting each of the 2 profiles I always use. The 3rd profile, which is the default-release running a different email, still seems to work normally. Thunderbird 115.10.1

I have tried Windows (10) safe mode, as well as thunderbird Troubleshoot mode and working offline, but the issue continued to occur.

I'm at a loss now as to what could cause 2 profiles to suddenly cause it to crash. By the way, one profile is for a gmail account and the other one is for an Outlook account, so they don't seem to be related.

In case it helps, there were 2 Microsoft Visual C++ programs installed or updated, and updates to Microsoft 365 and Google Drive just before the problem started. These were all auto updates in the background.

Any help from the Community would be greatly appreciated. Thank you!

This happens each time I open up T-Bird. Somtimes it is Yahoo.mail, sometimes it prompts to log onto aol.mail.com.

How can this be stopped?

________________________

desktop Win11 pro Thunderbird 148.0 (64-bit)

Connection to pop.mail.yahoo.com times out and no emails are downloaded. A new windows appears from https://login.yahoo.com/ that I have never seen before asking for username and password but this returns a "something went wrong" error. Is there an update, or a setting change, that resolves this problem?

Thanks

Frank

Normally, I can right click and tell Thunderbird that this is NOT junk, however, when I do this, these emails go back into the inbox and virtually instantly return to junk.

This is from anyone's email address that arrives from one particular website: @legacydigitalagency.com

I haven't come across this issue since I started using Thunderbird 20+ years ago.

I have both a Microsoft 365 email account and a outlook.com email accounts. I'm using version 148.0. Both account set up just fine. When I delete an email from either account after a couple of seconds I get a message saying "The current operation on 'Inbox' did not succeed. The mail server for "the account name" responded; [TRYCREATE] The destination mailbox could..." that all I can read. Why?? It is only on the Outlook accounts. I have several other account set up and they all delete the emails.

Dears since yesterday i cannot download yahoo mails to thunderbird on my windows computer. when thunderbird gets new messages, a window pops up asking me for yahoo account name and password. when entered yahoo gives the following message: " Something went wrong. We could not sign you in. Try again from a different device." i use thunderbird 148.0 on windows 11 (out of china, with Astrill VPN - all other websites work normally with VPN). i have three different yahoo accounts, the first time thunderbird asked yahoo first mail and authentification went through, but it does not go through for the remaining two accounts. i verified that OAuth2 is set up for all accounts. password is correct (as i can still receive emails on iphone mail app). cookies can be accepted without any exceptions, can see the whole OAuth2 dialog panel. i did all steps for setting multiple accounts. i verified all accounts for POP and STMP server settings. also mailnews.oauth.usePrivateBrowser set to TRUE. After all this, it still does not work (i also restarted thunderbird and the computer), what else can i do? Regards Violaine