Thunderbird Community Forum

Hi there! I and my colleague encounter some bugs with Thunderbird and we would like to seek your advice in regards of the issue.

1. <user a@citizen-systems.com.hk> was supposed to get a cc copy of the email sent by <user b@citizen-systems.com.hk> at Mon, 12 Jan 2026 09:35:19 +0800 but it never reached. The receivers, namely <user c@systems.citizen.co.jp> and <user d@citizen-systems.com.hk>, however, were able to get the mail. <user d@citizen-systems.com.hk> and <user a@citizen-systems.com.hk> are working at the same office and under the same network. Network provider checked the protocol, router, traffic and firewall are working as normal.

2. <user e@citizen-systems.com.hk> found a number of emails that she kept at "Inbox" disappeared on 12 Jan 2026 morning +0800.

She is unable to find it anywhere at her whole mailbox but has to ask the senders to resend them to her.

It would be very much appreciated if you can check and advise how to prevent the issue from happening again.

(PII redacted by moderator)

Hi! I am trying to use the Thunderbird application to help me view a huge '.mbox' file from an email account that is no longer active. I have the entire file saved to my computer as I downloaded it before the account was closed. Can you help me access those files? I am working on a huge project and really need to look for date sand times of emails sent in the mailbox so that i can piece together the timeline of the project. I would greatly appreciate this!!!

I can receive, but not send, emails using Thunderbird on my PC. I believe this problem began when Thunderbird was updated on 1/13/26. I have no problems sending email on my tablet.

My service provide does not support TLS 1.2, so I tried changing security.tls.version.min to 1. This did not help.

The attached shows the error message and my SMTP settings (1st image) and my service provider's email server settings. I tried changing the SMTP port to 587, but this resulted in a time out error.

Any help is appreciated, Norm

My old email server was Mediacom (mchsi.com). I had that email account plus a gmail account on Thunderbird. Sometimes people said their emails to my gmail account would bounce. I changed email servers and no longer have the mchsi.com email or Mediacom server and have 2 gmail accounts on Thunderbird. The new one works fine. When I send an email to the old gmail account it bounces back saying "address not found. Your message wasn't delivered to ------@mchsi.com because the address could not be found or is unable to receive mail. 550 5.1.1 I had the tech that sold me the PC look at the settings on Thunderbird for the gmail account and he said they were okay. Where else can he check? Somehow the pc thinks that just that one gmail account is run through or attached to mchsi.com Kathy foggiak@gmail.com

1. I've drafted an email, then hit save / closed the email and opted to "save changes". 2. I try to edit that email, but it is just "flashing" in the preview screen. I right click on it to "edit draft message", but that just brings up a blank email. 3. The status in the bottom left of the screen shows "loading message..." "downloading message", repeatedly. 4. It was working fine earlier in the week, but Thunderbird Desktop Version 140.7.0esr | Released January 13, 2026, seems to be when the problem started?

Just installed TB 147 under Windows.

Previously, there was a menu item File/Compact Folders (plural).

It is now (at least on my machine) replaced with File/Compact Folder (singular), which only compacts the currently active folder. I cannot now find a way to compact all folders at once.

What am I missing?

Why did retrieving messages suddenly stop. It was working yesterday and I made no changes to anything. I can send successfully. I am using Shaw/Rogers Pop server.

Why does "test connection to server" fail?

Hi, The question is in the title. I have imported my Outlook data in this 32-bits version (updated to 140.7) . I would like to keep them in a 64-bits version (147). I didn't find the solution. Thank you for helping me. Michael.

I can no longer send emails. I can send them through mail web browser and was in touch with their technical support and the problem is not on their end. The message I get when trying to send an email is: "Sending of message failed. The message could not be sent because connecting to outgoing server(SMTP) Promail.ptd.net failed. The server may be unavailable or is refusing STMP connections. Please verify that your outgoing server (STMP) settings are correct and try again". I checked my outgoing server settings and they are correct. I started Thunderbird in Troubleshoot mode and the problem still occurs. I started my Windows 10 in Safe Mode and the problem still occurs.

Hello:

I use Thunderbird for work. I have several email accounts configured in it, including Gmail, my company's email, and Outlook. I recently added a new Outlook account, and I haven't been able to send a single message. The error I'm receiving is the one described in the title. It's worth noting that I have another Outlook account working perfectly. I've tried every solution I've found online, and none of them have worked, including enabling SMTP in the account settings, making sure OAUTH is enabled, using smtp.outlook.com or smtp.office365.com instead of smtp.mail.outlook.com, enabling two-factor authentication, changing my password multiple times, etc.

I've read this is a common issue but hoping maybe things have changed? Trying to make a filter that says move to the junk folder email where subject starts [SPAM] (the hosting service adds that) UNLESS the address is in an address book, BUT I also need to accept everything from numerous domains. I see work arounds "if the address ends in @somedomain.com" but then I'd have to do that for every domain I want to receive from. Any email from any address where I have put *@domain.com in my address book should be let through. But I know TB doesn't accept wild cards in the address book. There MUST be some way around this? Thanks.

the Thunderbird inbox does not display received emails and does not display new emails.My web host provider,Hostgator, has all the old emails and is receiving new ones. so they are in their files. So the problem is with thunderbird. I have consulted your support and forums, tried troubleshoot mode... When I right-clicked on the input file and clicked on repair the display went blank and the emails vanished....also at midnight

on 1/16/26 I no longer receiving new emails.

your help will be appreciated

Lance

Hello, I have a problem with sending out emails. I can receive them but not send. when I set up an email and click on send, it does the spellcheck then attempts to send it, then a dialogue box comes up with: 'log into server smtp.iprimus.com.au with user name janas_3 failed'. It gives me the options of: Retry, Enter new password or cancel. I have tried using the existing password, and a new one and nothing works. I have contacted my Internet provider, who checked all the account settings, which were correct. Their advice was to contact Thunderbird for support, can you help me please?

I just installed Thunderbird on an up to date Windows 11 PC and unchecked the box Automatically mark messages as read, but it keeps marking all of my messages as read.

Help please!

A search showed that others have experienced this same error message, but as far as I can tell, they all were unable to access their email. These messages began appearing about a month ago. They pop up in Troubleshooting Mode. They did not in Windows Safe Mode. AVG and ZoneAlarm are not the culprits.

I've (finally!) managed to set up a new account on my new PC (having found the required password, a long string of letters - where did that come from? - I would certainly never have chosen that and I was never informed of it). I also successfully managed to transfer my Profile from the old PC to the new one (thanks to your helpful article. However, While I have thousands of 'sent' messages I only have a few in my inbox and sub-folders (i.e. today's). (I originally used the recommended server settings (?IMAP) I was offered but then changed to SMTP/POP which is what I always used before without problems.) So - I go to 'Import from a Thunderbird profile' and it shows me the Profile Name and Directory details, but then says 'Nothing can be imported from the selected source' - but doesn't tell me why not, nor what I should do about it! Given the Profile has transferred successfully, why can't it be accessed? Any ideas appreciated. Thanks, David Collins.