Thunderbird Community Forum

One of my two outlook email accounts no longer appears in Thunderbird, which says it is authenticated but not connected. This happened suddenly. I can still get the messages by going onto outlook.com. How do I get it back on Thunderbird?

I am using the Thunderbird software (140.7.1esr 64-bit) for mail merge purposes on a Windows 11 operating system. However, when I start the mail merge process, it begins initially but then automatically disconnects before completing the task.

Due to this issue, I am unable to complete the mail merge properly. Kindly look into this problem and provide a solution as soon as possible.

Thank you.

I was using MS outlook and recently I could not connect. Apparently ATT made a change so that instead of a password you need a Secure email Key. Since I needed to make a change I thought I'd try Thunderbird mail, but I still need the KEY. After a number of efforts with the ATT AI and human support people I could not find where the Key is entered on ATT. Now I know this forum is about Thunderbird and not ATT, but there must be Thunderbird users that have ATT and have made a seccussful connection. There are a few ATT help pages that outline how to do this, but each time I look at my ATT profile I can not find where to enter the Secure Mail Key. Is there anyone that can help me with this? THanks Mike

I received this message: Unable to connect

The connection was refused when attempting to contact localhost.

   The site could be temporarily unavailable or too busy. Try again in a few moments.
   If you are unable to load any pages, check your computer’s network connection.
   If your computer or network is protected by a firewall or proxy, make sure that Thunderbird is permitted to access the web.

I am not receiving new email. What do I need to do to get it working again?

I’m using Thunderbird to connect my Hotmail account. The setup shows as “successfully added,” but an error message appears:

“The operation on Inbox did not succeed. The mail server for account responded: User is authenticated but not connected.”

Previously, the connection worked perfectly, but starting this week, Thunderbird can no longer access or sync the hotmail mailbox.

How to fix this problem!!???

In Thunderbird account setup, I correctly enter my email account, name and password. I know it works because I can open my email on the Spectrum login page. I get a confirmation green box then when I press done a yellow box says unable to login at server, probably wrong configuration, username or password.

Hi! I hope you are well. It's my first time trying Thunderbird. I have the Linux Mint app. (seems to be the latest version available from the Linux Mint app store)

I attempt to sign into my Outlook.com email address on Thunderbird.

When I type my Outlook email and password and click Done, Thunderbird says configuration found in Mozilla ISP Database and it tries to pop up a browser window. Some website like login.microsoftonline.com is in the URL bar, but the browser window closes immediately without displaying a page.

Thunderbird say authentication failed. Either the entered credentials are incorrect or a separate username is required for logging in."

What do you think about the cause of this issue? Is this possibly an issue with my Outlook account or the Linux Mint version of Thunderbird?

I found a similar issue mentioned from a few years ago:[https://www.reddit.com/r/hyprland/comments/17q16cg/thunderbird_authentication_window_is/ https://www.reddit.com/r/hyprland/comments/17q16cg/thunderbird_authentication_window_is/ ] Where they used Linux and Thunderbird would open and close the Outlook window without giving a chance to login to the Outlook account.

On my computer, I tried: type a yahoo address into Thunderbird and click done and it opens a Yahoo website login window. So Yahoo seems to work, Outlook doesn't. Outlook's login window disappears by itself.

I was wondering if you have any suggestions for me? Is this the wrong place to report bugs (if you think its a bug)? (The Thunderbird app takes me to this place when I click Help > Share Ideas and Feedback.

Thanks so much for your time. :-)

Thunderbird info: Thunderbird for Linux Mint mint-001 - 1.0 140.8.0esr (64-bit) Linux Mint 22.3 - Cinnamon 64-bit

Hi all,

everytime I open Thunderbird I get a popup window from Yahoo finance with a server timeout message. I am unable to connect to get my emails through. I need to log on directly to Yahoo mail, which is a pain.

Hopefully someone can help me with this.

Find attached the popup image.

Regards

I have a new laptop with windows 11 (previously had a computer with windows 10) I got Thurderbird onto my new laptop however when I try to get in emails it keeps asking me for a new password. I keep entering the password for my provider but it does not remember it or does not accept itl It says its trying to connect to server but never does. then after a while it says it timed out. Is there another password I should be using?

Hi, Since up-date of Thunderbird on 02/25/2026, there is no more links nor update in my google agenda in thunderbird ( 148.0 realesed ). ?? Have you got any solutions? Regards

I have spent most of two days trying to Thunderbird to send email. It has worked perfectly for years. Suddenly, emails end up in Sent folder but go nowhere. My email host service sees nothing wrong. I can send emails through webmail and usually through Outlook. I have spent most of the day getting coached by Copilot and I am quite sure I have all the settings the way that worked flawlessly until two weeks ago. Is Thunderbird just dead and I need to go to Outlook?

Thunderbird Version 140.7.1esr, Build ID 20260123195141 User Agent Mozilla/5.0 (X11; Linux x86_64; rv:140.0) Gecko/20100101 OS Linux 6.1.0-33-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.133-1 (2025-04-10) OS Theme Xfce / Adwaita Application Binary /usr/lib/thunderbird/thunderbird-bin

Having a problem with an ATT POP account. TB stopped getting mail. After a minute and a half or so (wish it would time-out faster), I get a pop-up box in the top right of the screen that states: "Connection to server inbound.att.net timed out" and then quickly goes away.

Deleted passwords and cannot see where to create them again, as it never prompts me for new ones.

Thanks.

When I attempt to access the Add-Ons service through Thunderbird, it brings me to an HTML page (https://addons.thunderbird.net/en-US/thunderbird/search/?q=lastpass&appver=147.0.1&platform=Linux) reading

> addons.thunderbird.net > Performing security verification > > This website uses a security service to protect against malicious bots. This page is displayed while the > website verifies you are not a bot.

with the following footer: > Ray ID: 9d07fae58cabaefb > Performance and Security by Cloudflare

It will attempt to connect to Cloudflare to verify a Captcha, but the Captcha itself never renders, and after a period adds the following to the text:

> Why is this verification taking longer? >This verification can take longer due to an older computer or a slow internet connection. > What to do next: > # Wait briefly. Refreshing the page will restart the security verification and may take longer. > # If the verification still does not complete, refresh this page. > # If you are still stuck on this page after a page refresh, refer to Cloudflare’s troubleshooting documentation for more help.

After another period it then cycles the verification page. This continues as long as the tab remains open.

Opening the link listed above in Firefox opens the Addons page as expected.

Similar Captcha pages open on launch, as well as when accessing support or attempting to create a Matrix chat account.

There is a potentially related issue in that images and some icons are not rendered. I will make a separate post asking for help with that if it is not related, but it seemed relevant to mention.

The problem has existed for a long time, and I have checked existing responses without finding a solution, but I didn't get around to asking about it until now.

I am using Thunderbird v. 147.0.1 (64-bit) for Linux with no extensions installed), connected via AT&T broadband service with no proxy set, running under Manjaro 26.0, kernel 6.18.8-1, with the XFCE desktop environment (that last is only mentioned for the sake of completeness). I am using GUFW for my firewall, but the problem persists when the firewall is disabled (something I do not wish to do regularly in any case).

I am setting up a new computer with Linux Mint and Thunderbird. I got my primary comcast.net account added in and working but when trying to add another account I get the following:

Unable to connect

The connection was refused when attempting to contact localhost.

   The site could be temporarily unavailable or too busy. Try again in a few moments.
   If you are unable to load any pages, check your computer’s network connection.
   If your computer or network is protected by a firewall or proxy, make sure that Thunderbird is permitted to access the web.

Since the first account works, I assume there is no problem with network connection, firewalls, or proxy settings. I have confirmed spellings of username and password. Any ideas?

Greetings.

For many years I have used Thunderbird to send and receive mail through my Outlook account (while happily donating to Mozilla).

A few months ago, every initial attempt to send a message abruptly started to fail, generating the dreaded notice that “the message could not be sent because the connection to Outgoing server (SMTP) smtp-mail.outlook.com timed out.”

What is odd is that if I keep trying to send, the message always goes out eventually -- sometimes after only two tries, sometimes after ten tries.

Thus, my Outlook account works, my Thunderbird settings work, the SMTP server works -- but only at random intervals.

The problem has continued through several Thunderbird updates, including the current one (147.0.1). I tried changing the server to smtp.office365.com and got the same performance.

I am on MacOS 15.4 and am not running any third-party antivirus or firewall product.

My thanks to anyone who has insight into this problem.

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?