Thunderbird Community Forum

Not sure where to post a feature request, but I use a scheduling app (Playtime Scheduler) that consistently offers ics files with an empty LAST-MODIFIED field. So I have to manually edit the ics file every time before it can import into my calendar.

Would it be hard to make Thunderbird ignore an empty field like that and import anyway?

Hello

I use Thunderbird for many years, I have a profile weighing 3,6 GB now… I already moved this profile on my old computer, from default location to a data disk. Now I needed to move it to a new computer, so I moved it to my Dropbox (with local storage on both), to conveniently access it from the new machine, and to have some kind of backup (with a real backup, more occasional, of course). I don't plan to launch Thunderbird from both computers, so there should be no conflict.

I installed a fresh new download of Thunderbird (152), which I just upgraded to 153. The new computer runs Windows 11 Professional (build 26200.8875), has 32 GB of memory and a large amount of free disk space.

My profile.ini file currently looks like: ``` [Install734AE0B000379192] Default=C:\Dropbox\Applications\Thunderbird\0q9jw2nn.default Locked=1

[Profile1] Name=default IsRelative=1 Path=Profiles/ncc2rvps.default

[Profile0] Name=default-release IsRelative=0 Path=Profiles/30jrlwud.default-release

[General] StartWithLastProfile=0 Version=2

[Profile2] Name=PhiLho IsRelative=0 Path=C:\Dropbox\Applications\Thunderbird\0q9jw2nn.default Default=1 ``` Profile 0 and 1 were created at installation time. I added the Profile2 and I set StartWithLastProfile to 0 to ensure the profile manager sees the profile.

When I start Thunderbird, after choosing the PhiLho profile, I end up with an empty window: no accounts, no messages, no folders, etc. I see no relevant error in the developer console, or the logs. What I am missing?

No new messages have downloaded since July 31. I am very disappointed as there are several things I need to access and no way of getting support. I feel like I keep trying to email and ask questions but by using my Gmail and not my current WB for me.com email it is confused and I have been looking on Mozilla support for similar questions, but seem very overwhelmed and have tried a few of them and restarted it several times but not resolving the issue. Can someone please help and if possible give me a call <redacted>. I’m not sure how I’ll get the answer if any from this site but hopeful that it is sooner than later because I really need to get it done today.

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?

Здравствуйте у нас перестали работать метки помечаешь письмо меткой и оно сначала уходит куда надо в папку с этой меткой а потом заходишь она опять в изначально метке стоит, до 28 июля все было норм а потом начало криво работать и поиск тоже не все письма ищет раньше все показывал а теперь не все и приходиться искать по тексту сообщений тогда находит.

I want to copy my windows Thunderbird profile to Linux but my Profile Directory will not open when I press open directory. I downloaded Thunderbird from the Zorin app store, and it may be a flatpak or something – it won’t tell me now because I have already installed it – but I believe that could be a reason for the directory not opening. Is there a non-PC-literate way of finding out and fixing this?

Every five minutes Mozilla sends me a page asking for access to my Google account. I click "deny" and it goes away for a few minutes, but comes right back. And while it is on, I can neither send nor receive email. Is there some way to get it to go away and stay away? Thanks, Larry Wright

All was well until about six months ago. When I try to connect to my provider TB won't connect. BUT. At other times it will connect then every few minutes will try to connect again - then again .... I get this message "Connection to the server mail.comcast.net timed out". Then I get this message each time it fails "Login to server mail.comcast.net with username 170834000 failed". It keeps asking me to input my password even though everything is working appropriately. Then at other times it says it doesn't connect but it has connected and it still continues to ask me for a password.

I have uninstalled TB and reinstalled it thinking that would fix it - it didn't. I have changed my password - again to no avail. I let TB choose where to put things and configure each item appropriately. I don't try to get in the way of what works.

Comcast is apparently getting out of the email business and asking everyone to move over to their chosen substitute (Yahoo.mail) and I have not chosen to migrate at this point. Maybe that's the problem. This is the message I get each time I log into Comcast.net:

"A better email experience is now available for you

You're invited to upgrade your email account to Yahoo Mail, so you can enjoy a more user-friendly experience. Your email address, messages, folders, and contacts will not change.

With Yahoo Mail, you'll enjoy enhanced security, a built-in calendar that's easy to use, AI-powered inbox organization, and a top-rated mobile app for easy access on the go."

I am not aware of any changes in the settings from before when it was working well and now when it seems to be erratic.

I am not terribly computer savvy, but I'm usually able to trouble shoot and fix the issues that confront me. This time I'm out of my league! I need help.

Thank you for helping me.

I prefer to have the Contact Name only display in the TO: field of composed or outgoing emails. I already know their address is correct in my Address Book, why do I need to see it? Presently, the TO: field shows "Name <email address>", as shown in the first uploaded image.

I am a new user to Thunderbird and I have reviwed, and believe, set all the Settings correctly that I could find on the subject (see second uploaded image), but the results do not change.

What am I missing?

Thanks Matt T

I am assisting an elderly user with a personal @hotmail.com account that receives email successfully in Thunderbird but cannot send. I have confirmed they can send and receive emails from their online outlook.com portal. The user's computer setup is as follows:

• Windows 11 (with latest updates).
• Thunderbird 153.0.2 (64-bit).
• A personal @hotmail.com account with the following server configurations:

  -> Incoming IMAP: outlook.office365.com, port 993, SSL/TLS, OAuth2, and
  -> Outgoing SMTP: smtp-mail.outlook.com, port 587, STARTTLS, OAuth2.

Thunderbird successfully authenticates to Microsoft using OAuth2 for incoming email. However, when Thunderbird attempts outgoing email authentication, Microsoft's SMTP server rejects the authentication. The Error Console in Thunderbird records this message: "535 5.7.139 Authentication unsuccessful, SmtpClientAuthentication is disabled for the Mailbox."

-> Refer to attached image: "Thunderbird Error Console_20260811.jpg". -> I am able to provide a short screen recording demonstrating the failure if needed.

To try and resolve the above, I completed the following actions:

1. Confirmed Thunderbird is current (153.0.2).
2. Confirmed SMTP is configured for OAuth2 rather than Normal Password.
3. Confirmed port 587 and STARTTLS.
4. Re-authorised the Microsoft account/OAuth connection.
5. Confirmed IMAP OAuth2 works.
6. Confirmed Outlook.com webmail can send successfully.
7. Reviewed Mozilla's current “Microsoft OAuth Authentication and Thunderbird in 2026” guidance, including the section covering cases where IMAP/POP works but SMTP does not.
8. Captured the SMTP failure in Thunderbird's Error Console.

However nothing worked, so I raised the matter with Microsoft support and eventually had the matter referred to their Tier 2 team. The Microsoft case number is: 7107041963.

Microsoft Support confirmed that for a personal Outlook.com/Hotmail account there is no user-accessible mailbox-level SMTP AUTH setting, and advised that SMTP is enabled by default for supported clients. However, because sending from Outlook.com webmail works, Microsoft Tier 2 declined to investigate the SMTP server response further and directed me to Thunderbird support.

I am able to provide a copy of the chat transcript if needed.

In any event, the TLDR version IMAP works using OAuth2, but SMTP using OAuth2 fails because Microsoft's SMTP server reports SmtpClientAuthentication is disabled for the Mailbox. Microsoft Tier 2 has referred the issue to Thunderbird support.

Questions:

1. Is this a known current issue affecting personal Outlook.com/Hotmail accounts using Thunderbird?
2. Is 535 5.7.139 SmtpClientAuthentication is disabled for the Mailbox known to occur with Thunderbird OAuth2 even though IMAP OAuth2 succeeds?
3. Is there a current Thunderbird-side workaround or alternative SMTP server/configuration recommended for personal Hotmail accounts?
4. Would changing the SMTP server from smtp-mail.outlook.com to smtp.office365.com be appropriate for a personal Hotmail account in Thunderbird 153, or should the current Microsoft-documented server be retained?

-> I note there appears to be conflicting advice on this point in previous support threads.

1. Given that IMAP OAuth2 authentication succeeds for the same Microsoft account, does this indicate that Thunderbird's Microsoft OAuth authorisation itself is functioning correctly, or could SMTP require a separate permission/token that may be failing?
2. Are there any additional Thunderbird logs or diagnostics I can provide that would help resolve this matter?

Disclosure: I used ChatGPT to help organise my troubleshooting notes and technical details for this post. The troubleshooting, observations and diagnostic information described above are from my own work on the affected PC.

I had Thunderbird on my Windows 10 computer. I bought a new Windows 11 computer and downloaded Thunderbird. When I try to set up my email account, I provide my full name (not my Thunderbird user name) and email address. The next screen has the message "Configuration found in Mozilla ISPDB ". I clicked on IMAP and hit continue. The next screen I type in my password for my Spectrum mail account. I have confirmed that the password works went I log onto the Spectrum website. The next screen has the Authentication error "Unable to log in at server. Probably wrong configuration, username or password.". I've also tried using my Thunderbird user name and Password instead of my full name and Spectrum password with the same results. I know my Thunderbird user name is correct but I can't be 100% sure that my Thunderbird password is correct.

I'm not sure if this matters but my email has the has the extension ----@socal.rr.com. This was assigned to me by my original email provider, which was Time Warner Cable. Spectrum bought Time Warner Cable a few years ago and I think Spectrum uses a different extension.

Please excuse the length of this but it's necessary.

Began using Thunderbird (TB) in June, 2026 accessing email from wowway using POP3 (I know not imap, but old habits die hard). Changed password on wow in July and changed it in TB. Thereafter, and up until yesterday, TB was unable to logon to wow. However, the new PW allowed access to emails by browser logon to wow; old PW failed as it should. Frustrated with not being able to use TB with new PW: - deleted AppData/Roaming/Thunderbird folder (profiles and all) - recovered a backed up copy of TB folder from mid June when things were working and copied it to AppData/Roaming. Bingo, was able to get and send emails. Puzzled, looked at TB Saved Passwords and verified the old PW was being used. To verify this, I sent an email to myself, pressed F5 to get mail and it was in the inbox, and also on wow server.. BOTTOM LINE: There is no question that TB is using an old, changed wow PW. And if PW in TB is changed to new PW, access to wow fails. How can this be? Help please.

There was an earlier Case with the exact same name as what I named this case which was archived back in 2025. I have been living with this same problem since last year also. In the previous case there was reference to "downgrading" to an earlier version of TB, but there have been a bunch of updates since then so I doubt that would fix my problem because that earlier version is now over a year old.

I have one Gmail folder that correctly has one folder label "Junk." However, I have 4 folders that are AT&T related (2 from the domain "sbcglobal.net" and 2 from the "att.net.") For some reason when I set these folders up years ago they started out as labeled "Spam" instead of "Junk." Of those 4 folders 2 of them have the duplicated "Spam" folders, one from each domain."

When I go to Folder Properties I see "imap://XXXXX%40sbcglobal.net@imap.mail.att.net/Junk" on one of these Spam folders and "imap://XXXXX%40sbcglobal.net@imap.mail.att.net/Bulk" in the other. And the same "Bulk" vs "Junk" issue is in the other domain as well. All are named "Spam."

Can I simply delete one of these folders that are named "Spam" in each domain? Does it matter whether I delete the one ending in "Junk" or the one ending in "Bulk?"

Thanks.

I was a satisfied user of the Thunderbird e-mail client. I especially enjoyed the ability to toggle into darkmode when browsing and reading my e-mail. The previous toggle I used to activate that feature is missing, and I cannot locate a work around to turn it back on. Any assistance would be greatly appreciated. Thanks

just got Thunderbird, i added my outlook email then got to the "connect your email setting" then i clicked continue cause i wanted to use imap and got a "Authentication error". I got Thunderbird on a different device and used my gmail on that device and it worked fine. Only get the error when i try to use my outlook email and i don't know what to do.