Thunderbird Community Forum

Running Win10, all the sudden I'm getting Not Responding messages, failures to connect to server, and slow deleting of emails. I tried everything: uninstalling/reinstalling; running on troubleshooting mode; checking compatibility. Nothing works. Any ideas?

Thank you

Whenever I do anything with email I get a message "not responding" which causes a delay for a few minutes before it proceeds This occurs with almost every action Open email, delete email, browse a different folder (eg Inbox to Sent) it suddenly started happening yesterday

Goal: I have outlook on a windows 10 desktop with many .pst files I want to keep (emails in folders and contacts)/import into TB. I want to set up Thunderbird on a new laptop PC and use TB instead of Outlook.

I'm setting up Thunderbird first on my desktop but I don’t know how to import the outlook files – one Q&A answer says first install an older version of TB that can do the outlook import (I started this and it couldn’t find my account so I got stuck); another Q&A answer says the outlook files have to be ‘offered’ to Thunderbird and may or may not be.

Can I have human help? I’m happy to pay. Otherwise I don’t think I can figure it out and I’ll just stick with Outlook. I see someone else switched to TB and then went back to Outlook. Hmmm. I wonder why?

Thank you so much. It sure seems like a great product you offer but it's overwhelming figuring out how to get there from here.

I received a spam message this morning that had a "Disposition-Notification-To" (aka Read Receipt) line that had MY email address on it. I honestly don't know why a spammer would do this - but that's not the issue. I have Read Receipts disabled, but Thunderbird generated an email (to me) and sent it to my mail host. This seems like a bug. Even if the Read Receipt has my email address on it (making it mostly harmless), Thunderbird shouldn't have generated the message. Or am I missing something? Thanks.

On my PC Thunderbirds sending/receiving mail says the mail server refused my connection. My laptop works fine. I have duplicated my laptops in/out specifications onto the PC but still nothing works. Spectrum says everything on their end is fine but can't vouch for roadrunner who is the rr in my mail address of ca.rr.com. All this started about 4 days ago. Any ideas on what to try next? Thanks.

A "send later" button came up one morning instead of the usual "send" button. When I clicked on the write button to see where the "send" button was, several choices came up but when I clicked on the "write" choice I lost the other choices and now can't get back to the original write button and still no "send" button appears anywhere on the menu. I can save messages to Draft but still can't actually send them. I can still receive emails, just can't send them! Help!

Recently tried to switch back to using Daily, but now I get authentication errors each time I start the program. It's always the following three errors in sequence: Authentication failure while connecting to server imap.gmail.com. The certificate for imap.gmail.com does not come from a trusted source. Non-overridable TLS error occurred. Handshake error or probably the TLS version or certificate used by server imap.gmail.com is incompatible.

I've tried getting rid of all of my saved passwords and even completely getting rid of the account and re-adding it. I've also tried completely disabling my VPN's service in Windows to see if that was somehow affecting it, but nothing.

Hi, I was just contacted and completed a survey, and signed up for your newsletter. I saw what looks like new products. I wondered if I need to download/upgrade?. Thanking you

When my message filter uses the "Reply with Template" action, the reply e-mail is always PGP encrypted, even when I do not have any public key for the recipient e-mail address. As a result, the reply e-mail is always corrupted.

I am using Thunderbird 140.7.1esr on Windows 10.

I have attached a screenshot of what the reply e-mail always looks like.

In the Template that I am using, the "encrypt" button is not selected, and in the OpenPGP menu of the Template, the "Encrypt" menu item does not have a checkmark next to it.

Does anyone know how I can get Thunderbird to send reply e-mails without using encryption?

Hello,

Everything working just fine last night. Wake up and Thunderbird will not retrieve emails.

Remembered this old message I got so I went through and deleted my second email address, didn't help.

https://support.mozilla.org/en-US/kb/thunderbird-and-yahoo

Checked all settings compared to Yahoo, still won't download messages. I can even send a message with my current settings no problem, and it does login, just won't retrieve emails. Gives me a connection timeout.

Anyone have any ideas?

Why does the Thunderbird search for an email with certain information no longer work? It used to work OK. Now it usually fails to find any messages with the selected data. eg search for all messages that have jv16 in either the subject or body text. I know there are several in my Thunderbird but they are no longer found by the find function (although they do exist as found by a manual search).

Can not send emails to a newly created outlook.com (free) account. Have tried dozens of different settings, approaches.

My current setup:

 - windows 10
 - thunderbird 140.8.0esr (64-bit),  numerous previous versions also do not work
 - outlook.com (free) account mail provider
 - POP3 enabled (tried IMAP enabling also) on outlook.com account
 - no 2FA or 2FA enabled on outlook.com account, no difference
 - outlook.com web access works fine
 - followed instructions in mozilla support article Microsoft OAuth Authentication and Thunderbird in 2024 
      (https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202)
 - have done a fresh install on a new machine without an existing profile.
 - have tried various microsoft servers, have tried oauth2, normal password
 - thunderbird account creation works just fine.
 - server settings and SMTP settings match as recommended by support article noted above
    SMTP server settings
        server name: smtp-mail.outlook.com  
        port: 587
        connection: STARTTLS
        authentication: OAUTH2
        user:  xxxxxxxx@outlook.com

symptoms:

 - receiving(downloading) emails works fine.
 - sending emails fails with following messages
     Login to server smtp-mail.outlook.com with username  xxxxxx@outlook.com    failed    followed by 
           Unable to authenticate to Outgoing server (SMTP) . Please check the password and verify the 
             'Authentication method' in 'Account Settings | Outgoing server (SMTP)'

Many people seem to be having this issue with no resolution.

Please help.

Good morning

Since this morning (05/03/2026) Thunderbird freezes within a minute or two of opening the program.

Everything in the program freezes up. I cannot even close it.

I am running Version 140.8.0esr on a Windows 10 PC.

Initially I was getting a pop up warning message that ask me to confirm if I wanted to send an email with attachments of over 20 MB. There were 3 or 4 such messages. I had not tried to send such emails.

I checked the Outbox in Local folders for old messages, but it was empty. I also checked the Unsent messages files in Local Folders in the Profile folder. I deleted the Unsent Messages.msf file to no effect. I renamed and replaced the Unsent messages file. Also no change.

I checked for crash logs but there are none.

I have run out of ideas as to what to try next. Does anyone have any advice?

I have a domain so any email I use comprises of name@mydomain.co.uk

In the past I have given an email address to some dodgy enterprises such as Abbey National plc, and so I get loads of spam to abbey@mydomain.co.uk

It is an utter pain that many spammers use a throw away or random To: address but because the envelope email is abbey@mydomain.co.uk I get to receive it and there is no easy way of searching a folder to find matches to "envelope to".

Similarly it seems impossible to construct filters for an "envelope to" address.

Any ideas?

I posted this question some time back but didn't receive any helpful answers and don't know where my post is. In the upper right-hand corner there is suppose to be 3 symbols. One to lower the app, one to make the app full screen or partial and one with an X. I have jumbled symbols where the 3 good ones are. It does it in trouble shoot mode. I tried disabling addons but I can't get the normal symbols back. Here's what it looks like... Thank you for any help.

Hello, from time to time my Thunderbird on my desktop PC running windows 10 doesn't receive emails, while they arrived on my I Phone 8. Checked my Telstra web mail, all emails are there so what is stopping getting to my desktop PC? I thought the Thunderbird receives emails than synchronize with my I Phone? As you can see from my 2 images the Telstra is up to today as is my I phone But Thunderbird is 3 days beyond. Tomorrow it may back to normal or the next day? I am returning to this message the next day 16/06/2026 1 more message on my I Phone, still nothing on my Thunderbird.

An other problem I get with Thunderbird is that a message appears on the right bottom of my screen: "Mozilla Thunderbird Connection to server mail.bigpond.com timed out" and/or "failed to connect to mail server imap.telstra.com" If I try to send an email after the above notifications, I get the "Connection Refused". I know than to just walk away. I am using Starlink as Telstra here doesn't work as I am on the fringes of Melbourne in a BLACK HOLE. Any help will be gratefully received. Thank you for reading this. Regards Ilio Pieroni