Thunderbird Community Forum

Just opened TBird (Unified Folders) and scrolled down to empty Trash with 536 emails, as i started to scroll through several unread messages to see if any had incorrectly gone to Trash, suddenly the number of 'Trashed' messages increased to 8369, many of them unread  !!!

please advise

Imagine having more than 30 Accounts to be added on a single profile my concern is how will Thunderbird handles file size if it's using one file (MBOX) and if the file has no solution, can I create files and keep mails on them until they reach max size?

I am using MacOS 10.13, Thunderbird 115.15.16ESR: my Hotmail worked until 15 May 2025 and then it would not download new emails. Screenshots are available if you want me to post them. I got an error message: "authentication failure while connecting to server outlook.office365.com". I updated Thunderbird to the latest for my OS: 115.18.0ESR. Still no new emails. I deleted my email account on Thunderbird and tried to reinstate it. Now I get an error message when trying to set up the account: "Unable to log in at server. Probably wrong configuration, username or password." I tested my password by logging into my Microsoft account with it on my browser. I can also login to my email using Firefox, but I want my Thunderbird email client to work again.

The configuration I am using is: I use my normal hotmail password in the password field. I also set up a new App Password with Microsoft and tried that without success. With the 115.18 update there is a new field: Your login. I just put my hotmail email address in here. incoming: outlook.office365.com, port 993, SSL/TLS, Oauth2 
outgoing: smtp.office365.com, port 587, STARTTLS, Oauth2 (I have also tried: smtp-mail.outlook.com)

I enabled 2-step authentication with Microsoft in my Microsoft account more than a year ago. Interestingly, I don't get a prompt on my iPhone Microsoft Authentication App when I select Done when trying to set up the hotmail account on Thunderbird.

Please help. I am desperate, and I have wasted a lot of time on this without success. Cheers

After using Quick Filer or Search I am unable to go back to the folder I was using or to open any other messages on any of the three accounts I have set up.

I have to restart Thunderbird each time, is this a known issue or is there a setting somehwhere that I need to adjust?

Failure to download email from Optus. I have spent a number oif hours to no avail talking and typing with the Optus staff regarding this problem. 1. I can send email from TB but cannot receive. 2. I can see the incoming emails in their Webmail site. 3. Optus confirm my settings are correct for both the mail server and SMTP server. When I go to Settings> Security > Passwords > remove server so I can re-submit my password, the only one showing is the SMTP server. Should the incoming mail server also be shown?

I am frustrated and ready to dump TB but have bee with it many years and don't want to start again with another programme as I am 83 and am partially blind. Please can anyone assist?

Hi everyone,

I'm working on a privacy-friendly email setup and ran into a challenge with Thunderbird.

My setup: I have a catch-all email address that forwards all incoming emails sent to *@mydomain.com to my real mailbox, secret@mydomain.com. This way, I can use aliases like alias1@mydomain.com, alias2@mydomain.com, etc., without exposing my actual address.

This part works perfectly.

The problem: When replying to a message sent to alias1@mydomain.com, Thunderbird automatically uses secret@mydomain.com as the sender address. That defeats the purpose — the recipient now sees my secret address, which I wanted to keep hidden.

Thunderbird offers a workaround via identities, but it requires creating a separate identity for every single alias, which becomes unmanageable if you use a lot of them.

My attempted solution: My idea was to have my mail server insert a header like:

X-Alias: alias1@mydomain.com

Then, on sending, the server could rewrite the From: header using that value — thus preserving the alias and protecting my actual address.

However, I discovered that Thunderbird strips custom headers like X-Alias when sending. That breaks the solution.

My questions: 1. Is there any way to configure Thunderbird to preserve specific custom headers like X-Alias during sending? 2. Alternatively, is there a better or recommended approach to achieving what I’m trying to do — replying from the alias address automatically, without exposing the real one, and without creating hundreds of identities?

I’d really appreciate any ideas, insights, or suggestions. Thank you!

Updated to Thunderbird 140 for Mac (OS 18.5 and 17.x) and now cannot send emails -- on two different machines: one an iMac, the other a MacBook.

About 10 or 20 seconds after hitting "Send", we get an error message saying "Sending of the message failed. An error occurred while sending mail: Outgoing server (SMTP) error. The server responded: EHLO [13 hex characters] internal error AUP#EML-005."

Our settings and password have not changed, and they are all correct according to our ISP.

Hello,

We’re developing a headless, accessible interface to Thunderbird for blind users, and we’re integrating with the browser.messages.list() and browser.messages.query() APIs to access email content.

We’ve encountered an issue: the Thunderbird web extension API requires messages to be downloaded and stored locally to access their full content via the getFull() endpoint, but there appears to be no way to programmatically trigger a message download from IMAP using a message ID or header.

To minimize disk usage, we only want to store the most recent 30 days of messages locally. However, when we enable “Synchronize the most recent 1 month” in Account Settings → Synchronization & Storage, Thunderbird begins syncing from the oldest messages in the account (starting in 2008), rather than downloading the most recent month (e.g., June 15 – July 15, 2025).

My questions: Is there any way to configure Thunderbird to download and store only the latest (by date) 30 days of IMAP messages?

Alternatively, is there a way to use the WebExtension API to access the full content of recent IMAP messages without syncing the entire history?

I'm currently using Thunderbird 128.11.0esr on Linux (MATE desktop).

Any advice or workarounds would be greatly appreciated!

Thank you.

Peer Certification expiration - Why is this Pop-up showing up after many years of thunderbird use and why does it prevent receiving and sending emails. It wants a certificate or an exception with out adequate explanation or guidance.

I did not have account set up and because I couldn.t receive email confirmation could not seek help. I contacted Norton who appeared on the company example and they could not resolve. Given I could not get access thunderbird for assistance, I did an uninstall and reinstall. I lost my addresses but at least I was able to sent and receive emails again. the Pop up had gone away.

I set up my second email and when I completed this set up I was greeted by this pop-up. What is this all about and what are the risks. How is it resolved?

Hi, I wonder if anyone has had a similar problem - since a few days I get an immediate SMTP timeout in Thunderbird for some mail servers but not all. For Outlook the same server works just fine. Version 140.0.1esr has recently been autoinstalled. It is possible that the problems started when that version was installed but I am not sure about the timing. The email provider has no explanation and claims there is no problem on its side. Also, Thunderbird has recently asked me to confirm a server certificate for receiving emails. Usually when that happens I also get asked the same question when sending emails, but this time I did not get the question for sending, I just get the timeout message.

Thanks,

Magnus

I like to use specific font sizes, such as 11 or 12. Thunderbird appears to have only small, medium, and large font sizes. Does Thunderbird have specific font sizes?

I'm able to receive messages from Protonmail and Outlook after installing Thunderbird yesterday. Have not been able to send an outbound message to Protonmail. Error is "Send Message Error. Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) 127.0.0.1 timed out. Try Again.

I am able to send messages via Outlook. Outlook works no problem.

Any ideas on what to do for Protonmail to work?

This is a weird one. For a few months now, I've had to deal with either my email timestamps being wrong, or my calendar appointment times being wrong.

I'm on Linux. I can replicate this with both the Flatpak and my distribution package.

By default, my email timestamps are fine. But my calendar appointment times are out by around 17 hours (that is, Thunderbird says they are happening 17 hours earlier than they actually are). I compare this to my Fossify Calendar app on my phone, which I had to install recently so I had a single source of truth, which is always correct. (It uses davx5 OSE as a bridge)

So the appointments themselves...are fine. My other calendar app can display them okay.

If I want to get the appointment times to display correctly, the only way is to set an environment variable. Regardless of whether I set my timezone manually in Calendar settings or use the system timezone (which is correct!), nothing changes. This is the only way to get it to work:

``` TZ=Australia/AEST thunderbird ```

or:

``` TZ=Australia/AEST flatpak run org.mozilla.Thunderbird ```

Now, my appointment times are correct...but my email timestamps are off! They are 11 hours behind what they should be. Despite this being my actual timezone.

I don't know what else to do. Please, is there any way to get my timestamps consistent for both my email and my appointments?

(sequel to this thread: https://support.mozilla.org/en-US/questions/1506824 )

Everything was working fine and then out of nowhere I try to send an e-mail and get "The message could not be sent because the connection to Outgoing server (SMTP) mail.rima.net timed out. Try again." Nothing had been changed, it just couldn't send and I've checked the settings that all appear to be OK, but I still cannot send e-mail. I'm receiving e-mail, but cannot send. What could be the issue?

Had this problem suddenly crop up since the update of one of my accounts not sending mail due to timeouts. I've not changed any passwords or settings since I had it working last. The message is the "Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) [my workplace's SMTP server] timed out. Try again." one, and it's preventing me from sending any emails.

Specifics:

• It's one account (my work one: work runs an Outlook/Microsoft mail server).
• My personal account (gmail) sends fine. Both accounts recieve email fine too, so this is just one direction on one account.

Things I've tried:

• Switching my Firewall off makes no difference, so it's not a firewall problem
• It's not that the emails I'm trying to send are too large, one word test emails also don't send
• Extending the timeout time by 3x doesn't help

I also opened a second computer not yet running the latest version - the account worked fine. Then applied the upgrade and that broke things in exactly the same way as described above. So I'm pretty sure this is an issue caused by the upgrade in some way. Not sure if other people with Outlook servers are having the same problem or if there's any workaround available but would appreciate advice.

chasjones

Jul 15, 2025, 07:02 CST

Yesterday morning, my Thunderbird app. was automatically updated..... since this occurred, I have not been able to compose a "New Message" after clicking on the "+ New Message" button. What should I do to regain the ability to compose "New Message"?

I try to access my messages from an outlook.com account with Thunderbird mac. I get the error message "the STAT command did not succeed". This happened suddenly today without changing any parameter. POP is enabled on this account. Moreover on another mac with Thunderbird everything is correct with the same account. Cookies are enabled I tried changing OAuth2 to normal and changing back. No sucess. What could I try next? Thanks.

Finding the folder an email is in, search just returns the emails. I have never seen the "Search Box" or the "View in Folder" button. How do I find the folder my search result lives in? Or for that matter, how do I find a subfolder that got moved by accident?

2~3日前にも同じ状態にになったのですが、ヘルプをいろいろ調べているうちに正常に表示されるようになりました、ヘルプを調べているうちにトラブルシューティングを押していたのかもしれません。…が、今日ももんだいなくしようしていましたが、一旦停止してい、次に作業を再開すると　 またメールフォルダーが消えてしまってました。今回はトラブルシューティングもしてみましたが、全くどうにもならないのですが、 何とかメールフォルダーを表示するほうほうがないでしょうか？…私は視力が非常に悪く視界もごくわずかしかないので、PCの画面も読むのに時間がかかり。返事にも思うように打ちづらくいろいろと教えていただくのに手間をおかけしますが何卒宜しくお願い致します。