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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.

At one time, I was able to access my email with Thunderbird. Then Thunderbird stopped working, and I didn't have time to research why. Monday, I bought a new Macbook. After installation, Thunderbird says "account settings found." Then it asks for a password. My password no longer works. Instead, I get a message: "Authentication failed. Unable to log in at server. Probably wrong configuration, username or password." What, if anything, can I do?

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?

Hola. A ver si alguien me puede aclarar la duda. Al configurar una cuenta de correo de Movistar, se me piden uno parámetros, pero no la contraseña de la cuenta en cuestión. Lógicamente, no puedo configurarla. ¿Por que no se pide que introduzca ese dato tan importante? Por favor, ayuda. Gracias. Un saludo.

Adjunto captura de pantallas con los parámetros que se solicitan para configurar la cuenta.

I spend the last hour or so in sheer panic and doubting my sanitiy as an email I was just reading disappeared from every mailbox I have here (I have 8 mailboxes in Thunderbird) . Also for whatever reason search is missing from the title bar.

The email was "archived" by Thunderbird inthe "Local Folders" I never use local folders as local folders is silly in 2026 imo. I have my own mailserver which is perfectly save and backuped and stuf I don't need yet another location were mail can hide.

Anyway that was a bit of a rant. This would not have happend if this sille ¨Local Folders" didn´t exist at all. But I seem unable to get rid of it.

How do I remove ¨Local Folders" from Thunderbird?

Hi,

I used to scroll up in current message using Shift+Space, but it stopped working for a few days now. it's not mentionned in moving around TB, so I don't know if it was normal behaviour or a feature added by TB's arch maintainer.

What I need is an add to thunderbird.exe telling that every important informations are in my thunderbird's profiles mapp.

You can Email my Google account [redacted email from public forum]

Hi, Hoping I can get some help here, I couldn't find an answer in the search topics.

I have lost a few local subfolders. First the subfolders lost the emails contained in them and then the subfolders themselves disappeared.

I renamed the main folder just removing the year from the folder name and not long after that the above happened.

I have tried the following:

• Searching the help topics • Searching the forum • Closing reopening Thunderbird • I removed .msf files and restarted Thunderbird

I am not sure what I can do now.

Thanks in advance for any help.

I leave Thunderbird running on my computer at home to do filtering and to handle spam. My account is an IMAP account. I often get a dialog box saying "Applying filter [name of filter] failed. Would you like to continue applying filters?" When this dialog box has not been dismissed, filters (and handling spam) seem to halt. Until the dialog box is dismissed.

That's not the desired behavior IMO. I'd like for TB to continue applying filters no matter what, and to (perhaps) log the failure in the log file.

Am I missing a setting that does this? If not, can we change the default behavior so that spam filtering does not halt (maybe with an error message in the log file) ?

TIA!

tech details: MacOS 15.7.2, Thunderbird 153.0.1 (aarch64)

Currently using TB 153.0, Win 11 on desktop PC.

In past versions there was a progress bar on right end of the status line, along bottom edge of the screen, that showed progress while TB was compacting folders. That bar hasn't been visible in last few updates.

When prompted today, I allowed TB to start compacting. I'd permanently deleted a really big bunch of old emails in last few days, so probably a lot of space that could be recovered. I kept waiting and waiting and waiting, but without the progress I had no idea if TB was busy or possibly frozen. So I just left it alone. When I came back and tried to manually start compacting, it immediately said "Done, 0K saved". So it had obviously done the compacting.

If it's an option, how do I enable that progress bar? If not currently available, please consider restoring it in future TB updates. I -for one- think it's a very useful feature.

THX!

I am trying to migrate from Microsoft Outlook 2021 to Mozilla Thunderbird. I have successfully imported the email from a number of different email accounts. I would now like to import the archived emails held in a number of PST files. The import tool would seem to be what is required, but it does not seem to allow me to select the PST files that I wish to import. I am concerned that it will try to import all email messages from my Outlook 2021. Is there a way of restricting it to just individual PST files?

I have used Thunderbird for years, for two different work accounts and a personal account. I am retiring from one workplace, a small arts charity which runs occasional arts events for which I work from home using my own set up. My successor uses Outlook so I want to save relevant emails for them to be able to access previous correspondence if they need to. If I save relevant emails as .eml files into a folder in Dropbox, should my successor be able to open them in Outlook? If not, is there another solution apart from printing relevant emails to PDF and saving them? I am not a hugely techie user and generally find Thunderbird very straightforward! Many thanks for any advice! CathGuth

In the last month or 2, when I delete an email it does not show in the trash folder. I can wait from 5 minutes to even the next time I reboot my puter to finally see it it trash. Sometimes it sends it to the all mail or important folder instead of trash. And if I delete from there, it still takes tons of time to end up in the trash folder...if it even gets there. This seems to be getting worse by the day. I have clicked repair folder, no change, I have cleared Thunderbird's cache, no change. It's also now taking way too much time to load an email that contains a picture. This happens with at least 3 of these gmails. I'm at a loss here and extremely frustrated and about to change these gmails from imap to pop. win10 and TB is up to date. But it doesn't compact folders as much as it used to either. Any help appreciated

A few times I have missed messages that have have been inadvertently placed in the Accounts Spam Folder. Is it possible to to indicate that the Spam Folder has contents in the same way contents are indicated in other Account Folders?

I've been a longtime Thunderbird user on my desktop (laptop actually). I'm wanting to start using Thunderbird on my Android phone.

What I understand so far is that both the desktop and mobile have to have the same settings if I want to be able to send/receive (and have records) on both setups. I also understand that I need use IMAP settings.

In my situation, I believe I set up my desktop to be POP but to leave messages on server until I deleted.

So, my questions are these: Do I need to delete my POP accounts on my desktop first before adding the IMAP version of the account? If not, I can simply add the new account along side and then delete the old account. If I do need to delete the account, does deleting the account delete the emails as well? And how do I transfer any emails or sent emails from the POP to the IMAP?

In as much as I have several accounts to transfer, I want to make sure my step-by-step works well for one then I can proceed to all the rest.

Thx BobbyG:)

I am using thunderbird client on arch linux. I am trying to filter by adding "Reply-To" as a filter. If i look into the source of the email i am trying to filter (i get like 100s of spam messages and only the Reply To seems to be from the same domain in the end) the Reply-To appears in there.

Any idea how to fix that? The other rules work fine, this one only seems to not work