Forum der Gemeinschaft Thunderbird

I have been trying to add my accounts to Thunderbird and had good success with gmail but wasn't able for Microsoft accounts. As I said in another thread (can't find the message anymore), I have 2 microsoft email account (one live.ca and one hotmail.com) and they both don't work. I was able to add them in Outlook desktop app and EM Client (a non open source software i'd rather not use) through IMAP with success. IMAP is activated in both accounts and as per Microsoft documentation the server is supposed to be outlook.office365.com on port 993. eM Client magically discover IMAP settings to imap-mail.outlook.com instead. Thunderbird opens an OAuth page and then it redirects from microsoftonline.com to localhost and fail with "Unable to connect".

2FA not activated in one account, if that matters. I have nothing running on port 80 if that matters.

I am running Windows 11 Pro 25H2. After updating Thunderbird recently to the latest version, it is crashing immediately upon starting Thunderbird, not even bringing up the initial screen.

The message is

"Thunderbird has stopped working. A problem caused the program to stop working correctly. Please close the program."

In addition, it brings up the Mozilla Crash Reporter, which states

"We are sorry

Thunderbird had a problem and crashed. We will try to restore your tabs and windows when it restarts."

I do not want to lose all my old POP3 messages, etc.

Please help, Nina

I don't know what to do when February 29 is in my calendar, 2026 is not a leap year. I've found nothing to help me. I have the latest version if Thunderbird. Thanks

Hi - I can't seem to delete from my Yahoo Mail via Thunderbird.

With Yahoo's new mailbox limits I wanted to clean up my Yahoo mail box and Yahoo obviously does not provide any decent tools to support search and delete.

I downloaded Thunderbird and despite several deletion attempts my Yahoo mailbox still shows 160,000 emails whilst my Thunderbird client only 9,000 - so when I delete it is not syncing.

Most emails are deleted from Thunderbird however some are now reappearing (in Thunderbird). No deletions from Thunderbird are reachign my Yahoo mail inbox, however I can send emails from Thunderbird and see the sent and received email in Yahoo and I can add folders in Thunderbird and see those folders in Yahoo.

I tried several things

- immeadiate delete in Thunderbird - moving the emails to a folder in Thunderbird and then deleting from that and then deleting the the folder - I check this article https://support.mozilla.org/en-US/kb/thunderbird-and-yahoo and everything appears correct

I've had to pay for extra storage to get the code to make this post.

Mike

Have a new computer and when they transfered my information they didn't do my email. I finally got found it an downloaded it but now it won't accept my password. Plese help I'm getting desperate. Thank you Mary Ward

Threading - why does it keep coming back? I have just realised it's back again on my Thunderbird and I never knowingly turned it back on.

Why does Mozilla keep trying to force it on users?

This has been an annoyance for users for several years now and the message has still not got through it would seem.

For an open and user-facing organisation, this is strange behaviour that I just do not comprehend. Include it if you want, but make it optional and easily so.

I know this is only the community forum, not Mozilla, but one would think that a wise organisation would keep an eye on what their customers were saying & feeling.

Clearly, this is a very basic question which has undoubtedly been answered before, but I haven't been able to find it. If Thunderbird had an old-style Help feature with an index, I could probably look it right up. But coming to the forum is the only option the program gives me.

Hello,

Despite the fact that I have set Thunderbird to display messages as plain text, my needs are not being fully respected. If the message contains some form of markup, presumably HTML, the font size is not what I have chosen. Generally, the font size is smaller than what I have specified in the Thunderbird settings.

This is unacceptable. It is a usability / accessibility issue. If the user chooses Plain Text and sets a font size, they have done that for a reason. Which is accessibility. If Thunderbird ignores the needs of users and applies styling rules to messages, that is a failure state.

Is there some way to actually, truly, absolutely display all messages as plain text in a specified font, weight, and size? If not, what is the protocol for reaching developers so that they can respond to this issue?

Thank you

It has been going on for two days. I tried restarting in troubleshoot mode and it didn't turn on the "Show Password" button. The version of thunderbird I'm using is Mozilla Thunderbird.

I have saved my selected emails in different folders under Local Folder based on the subject of the email. Now I do not see one such folder where I had saved several emails for that particular subject/topic. Need step-by-step to restore that FOLDER from C:\users\myname\AppData\ ???

My issue described may not be Accessibility I chose in Topic above as that was the closest to match. Basically I am missing that Folder as I might have accidentally deleted from the current file that displays when I click open Thunderbird Mail.

With 03.04.2026 they began to notice that the attached emails in eml format (the attached emails have attached documents, mostly pdf) sent from yandex mail stopped opening. Everything used to open well. Eml also does not save to disk. If you send the same files via Gmail, everything opens. Program version 150.0.1

OS: GNU/Linux Thunderbird Desktop

Is it possible to set up a TLS client certificate for authentication with SMTP, as it is with IMAP?

It works fine on the K-9 Android client for both IMAP and SMTP.

Is there a reason why this hasn't yet been added as an authentication method for SMTP?

Thank you!

Best Regards

I have a small office with 5 stations to access our one email account and we'd used thunderbird for years, but the lack of integration between the stations meant we changed to Outlook and of course that's a shitshow, so I'm coming back to ask you my self (rather than the tech guy) if there's a way to set up thunderbird so that if desk 1 opens and responds to email 17, that all the desks can see both that it happened and access the responce that desk 1 sent.

We have an IMAP email account hosted locally (as in, not a gmail account, or the like).

I'd be more than happy to pay for a piece of software that I could use. I've used Thunderbird (and Eudora) for decades and I'd like to continue to support it. But moreover, I'd like an email server that doesn't limit my account size (I use email for "corporate history") and one that would allow my individual staff members to see everyone's activity in the email server.

I had most recently (like 6 months ago?) been using thunderbird. My Tech guy said it was the most current version, but I couldn't tell you what it was.

We run on Windows -- most on 11 but a couple still on 10 until I can take the time to set up the new computers.

I keep my mail (both sent and received) in local mail folders. My server is gmail, and sent mail is put in gmail's sent folder by default. Every few months, I copy those messages to a local folder, and after I back them up, I delete the server copy.

What to my dismay, I discovered today that only the message headers, and not the messages were present in the local folder, though they had been when downloaded. Looking at the file sizes, I found the sent file to be 0 Kb, and sent.msf 255 Kb, when sent should have been around 60 Kb long.

I have been able to restore the messages from backup (whew!), but I have no idea how then sent file was wiped out. I know I did not do it.

Has anyone else had this happen? Is there a preventive measure I should take?

Hello,

I am on Thunderbird 150.0.2 for Windows.

I am really suffering here. I need to change the font weight of unread messages. In a non-threaded list.

The default weight I get with my preferred font (Trebuchet MS) is not bold. It is BLACK. When I say BLACK, I mean ultra bold, display font, heading weight. Heavier than the boldest font that even exists in the font family. Thunderbird is creating this ultra mega black font by taking the bold font variant and applying a faux bold effect to it. The result is that the text is so heavy that it takes up twice as much horizontal space as the ordinary bold font variant. This becomes a usability issue because it's not possible to see the date, sender, and subject at the same time.

I have struggled and strived with userchrome.css. Spent hours combing through forums here and elsewhere. I've already enabled the mystery setting in the config editor. I put userchrome.css where it is supposed to be.

I saw a blog post from Mozilla that says "userchrome.css is not supported". What is the actual meaning of this? That it has been actively blocked from working anymore, ever, for anyone? Or that users are taking risks if they create userchrome.css? Why can't developers speak plain language? "Not supported" could mean many things.

When I go to the Style Editor, userchrome.css does not exist there. Which leads me to believe that user customizations are absolutely deprecated and we are not permitted to use userchrome.css.

I tried editing some of the rules in the Style Editor, but could not determine any way of actually storing the changes. When I click Save, I get a dialog where I can **EXPORT** the file. But I can't seem to actually save the changes, because CSS files do not appear to exist in the installation directory. It must be compiled into some library.

This is extremely unsatisfying and super frustrating. Just getting straight answers to things is super difficult, nothing stays the same for more than a couple months, and up to date information either does not exist or is not found by any search engine.

So, please help. I just need to change one setting, the font weight of unread messages. Since Thunderbird is allegedly open source, I thought I would have some ability to make such changes. But the Style Editor doesn't seem to actually be an editor, but merely a read-only interface to precompiled rules? If I wanted to change the font weight of unread messages, would I be forced to compile my own version of Thunderbird? I'm not competent to do that, and it would probably either prevent updates, or the updates would break my changes.

Please help, I am super desperate. I need to see the date, sender, and subject all at the same time. That doesn't seem like an unreasonable ask.

I would gladly pay for an email client that gives me control over my data *and* allows me to control the UI, but apparently that doesn't exist.