Thunderbird Community Forum

I am working with thunderbird on two locations and have problems moving contents between address books and entering new contacts into address books.

On location A I have created a mailing list X under my personal address book. I could fill it by copy/paste address and name from mails received. Then I created a cardav address book Y and somehow (ctrl + left mouse?) succeeded to drag and drop the entries from X to Y and synchronized it with a nextcloud cardav file.

Now I went to location B, created a cardav address book with the same credentials as on location A and got the Y addresses synchronized.

So far, so good.

Then I tried to enter new addresses in location B into this Y online address book. Problem - I could not find a way to add new contacts into a line with copy/paste like into the X mailing list in location A. New contacts could only be added via the "New Contact" form, no copy/paste.

Then I created a mailing list in my personal address book with the same name X. I could not find a way to copy the content of the online address book Y into this list (on location B). When I tried with ctrl-left button drag and drop, the target mailing list X was forbidden. Only copying to my personal address book would be possible. But at least this mailing list X offered again the copy and paste possibility in one line, but unfortunately the list was empty.

Then I tried it with export/import. I exported Y from the online book to a vcf file on my computer, then tried to import the file to my mailing list X, but I could not find a way to import the file to the mailing list X.

I can create a new address book and move the contents of the cardav book to it. But adding new contacts is possible only via the "New Contact" form where I cannot just copy/past addresses from emails.

Any suggestion how I can work with my mailing list contacts on both locations and easily enter new contacts with copy/paste from mails without having to use the form?

In thunderbird when I select Help/Troubleshooting information and than click Open Directory at Profile Directory nothing happens.

Operating System: Fedora Linux 44 KDE Plasma Version: 6.8.2 KDE Frameworks Version: 6.31.0 Qt Version: 6.11.2 Kernel Version: 7.2.13-200.fc44.x86_64 (64-bit) Graphics Platform: Wayland Processors: 8 × Intel® Core™ i7-7700K CPU @ 4.20GHz Memory: 16 GiB of RAM (15.5 GiB usable) Graphics Processor: Quadro RTX 4000

1. 1. Thunderbird connects to my IMAP/SMTP server but neither receives nor sends mail

I am having a problem with Thunderbird on Windows with a custom-domain email account hosted by Advika Web.

1. 1. 1. Account

Email address: `connect@synergyappstudio.com`

Mail hosting provider: Advika Web

The mailbox and password are confirmed to be valid because I can successfully log in to the provider's webmail using the same email address and password.

1. 1. 1. Server settings provided by the hosting provider

Incoming IMAP:

• Server: `mail.synergyappstudio.com`
• Port: `993`
• Connection security: SSL/TLS
• Authentication: Normal password
• Username: `connect@synergyappstudio.com`

Outgoing SMTP:

• Server: `mail.synergyappstudio.com`
• Port: `465`
• Connection security: SSL/TLS
• Authentication: Normal password
• Username: `connect@synergyappstudio.com`

1. 1. 1. What happens in Thunderbird

Thunderbird shows:

> Connected to mail.synergyappstudio.com

However, incoming messages are not downloaded and outgoing messages cannot be sent.

The SMTP error I received was:

> The connection to Outgoing server (SMTP) mail.synergyappstudio.com timed out.

1. 1. 1. Connectivity tests

I tested the server from Windows PowerShell.

Port 993:

`Test-NetConnection mail.synergyappstudio.com -Port 993`

Result:

> RemoteAddress: 103.69.196.146 > RemotePort: 993 > TcpTestSucceeded: True

Port 465:

`Test-NetConnection mail.synergyappstudio.com -Port 465`

Result:

> RemoteAddress: 103.69.196.146 > RemotePort: 465 > TcpTestSucceeded: True

Therefore, both TCP ports are reachable from my computer.

1. 1. 1. TLS tests

I also tested the actual TLS handshake rather than just TCP connectivity.

TLS 1.2 against IMAP 993 failed with:

> Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

TLS 1.0 against IMAP 993 produced the same result:

> Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

I also tested the TLS handshake against SMTP 465 and received the same "connection was forcibly closed by the remote host" result.

1. 1. 1. Comparison with Outlook

There is an important comparison:

The same mailbox **successfully connects and authenticates in Classic Outlook** using the same server and credentials.

However, I am using Microsoft Office Home & Student, so Classic Outlook is not available to me as a practical permanent solution for this business email account.

Microsoft's **New Outlook** also fails to add the account and displays:

> Sign in failed. Please try again in a few minutes. You may need an app password.

The mailbox does not use Microsoft 365 authentication. It is a conventional hosting-provider IMAP/SMTP mailbox.

1. 1. 1. Thunderbird troubleshooting already attempted

I have:

• Confirmed the password works through webmail.
• Confirmed the supplied IMAP/SMTP server names.
• Confirmed ports 993 and 465 are reachable.
• Confirmed SSL/TLS settings.
• Used Normal Password authentication.
• Used the full email address as the username.
• Tried Thunderbird with the supplied IMAP/SMTP settings.
• Reduced **Maximum number of server connections to cache** from the default 5 to 3 and then to 1. This did not resolve the problem.
• Restarted Thunderbird after changing the connection-cache setting.
• Tried Thunderbird's connection logging, but the generated log files remained 0 KB, so no useful log was produced.

1. 1. 1. Additional observation

Thunderbird displays "Connected to mail.synergyappstudio.com", but the account does not actually synchronize incoming mail.

The provider's webmail works normally, and Classic Outlook works with the same mailbox.

1. 1. 1. What I would like help determining

Could you please help determine whether this is:

1. A Thunderbird IMAP/SMTP compatibility issue with this particular mail server; 2. A TLS negotiation issue; 3. A Thunderbird configuration/profile issue; 4. A Windows/security-software interaction; or 5. Something specific to the mail server's IMAP/SMTP implementation?

In particular, I would like to understand why Thunderbird can establish the connection but cannot complete the IMAP/SMTP communication, while Classic Outlook works with the same server, ports and credentials.

I can provide Thunderbird version information, Troubleshooting Information, screenshots of the account configuration, or any additional diagnostic information you need.

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?

Hello! I'm having a problem where a specific tag keeps un-applying itself. I have a number of filters that look for specific words in emails, and tag them accordingly -- all of my other filters are working just fine, but one specific one has decided to stop working. It has exactly the same settings as the other ones, and when I manually run the filter, it correctly applies the right tag.

But, minutes later, the tag will un-apply itself, and I cannot figure out why. For some reason, an older message is staying correctly tagged with that filter, but newer ones un-apply the tag. This same filter and tag used to work just fine. Other tags on emails from the same source work fine, too.

I have several email accounts in Thunderbird where the email address no longer exists, at least on the specified IMAP server. Thunderbird is configured to not attempt automatically getting mail for these.

I had used Thunderbird 102 on Windows 10 for years, and in that version, my mail was kept in Thunderbird for those accounts (though whenever I opened any folder in them, I was somewhat annoyingly prompted to enter my credentials since the connection to the server was failing). To copy my profile folder to a new Linux installation, I updated Thunderbird to 153.5.1esr, the same version running on Linux, as Flatpak. My mail is still kept in Thunderbird on Windows, but with the same profile on Linux, Thunderbird "hid" all folders from the offline email accounts (apart from an "Inbox" folder that is shown as empty): the files are still there in the profile directory, and Thunderbird seems to find relevant emails in search, but opening them leads to a "No mail found" screen, and there is no way to access this mail from the folder pane. How can I make Thunderbird see my mail again?

As if that was not enough, on a whim I decided to attempt the "Repair folder" option on my Windows instance of Thunderbird, where the folders were still being shown normally. I immediately regretted not having made a backup of my profile (I only have one from version 102, where the data was apparently stored rather differently), since this just deleted all mail in the selected folder entirely, with the relevant file in the profile directory being empty. (The file seems to be somewhat different on Linux too, since copying it back to the Windows profile did not restore the mail in Thunderbird, and I would probably have to copy my Thunderbird 102 backup into an install of Thunderbird 102 and manually upgrade to my/the newest version to get it back.)

I know local folders would never be deleted like this, but there does not even seem to be an option to move an entire mailbox into a local folder, other than manually. It does not appear like Thunderbird has proper support for mailboxes that are no longer available. It would be undesirable to have all my mail in some new mailbox lost in the same way after I lose access to it. (Local folders would not really help in this situation either, unless you plan out exactly when your mailbox goes offline.)

Mozilla Thunderbird Snap for Ubuntuubuntu-snap-build - 1.0

Just want to open a 'compose a message' without the extra main window also opening.

Tried to ask AI - that was no help - no surprise.

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 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]