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After I did the 128.5.2esr update, none of my email accounts can get email with SSL/TLS on. It won't even try the server with SSL/TLS on. If I turn it off, then it can get mail. When I try to change to STARTTLS it will just hang showing checking server capabilities. Some accounts are imap and some POP3

Running Windows 10, version 22H2 updated 12/10/2024 OS Builds 19044.5247 and 19045.5247

Gmail works fine. I've tried the just about all of the things I have found online, but no luck.

Any suggestions? In the past I rolled back to a working version and that fixed it, but it hasn't worked this time. Would removing all of the certificates fix it? Didn't want to take that chance until I threw it out out here!

Thank you!

Hi

I have a problem with Thunderbird which might be a bit niche but here goes...

The first attempt at sending an email fails as TLS Record Layer v1 is used, the mail server sees this and hard resets the connection so sending halts. See attached Wireshark trace screenshot "Failed".

If I retry the send again Thunderbird uses TLS Record Layer v1.3 and the email goes out ok. See attached Wireshark trace screenshot "Success".

If I send another message immediately no problem but if I wait 20-30 minutes the above cycle happens again.

I have set the minimum TLS version in the config to 1.3 (option 4) and restarted Thunderbird but this has not changed anything.

Any ideas how I can fix this? It's a pain because automated replies don't work.

I have an email account with multiple identities (aliases), some of which I would like to add under the same OpenPGP key that I'm using for the main identity. I couldn't find any option in the OpenPGP Key Manager in Thunderbird which would allow me to add identities to the key. How should I go about doing this?

Over a month ago I began experiencing an error message when attempting to send emails from my gmail account using Thunderbird (TB). Error msg reads: Sending of the message failed. An error occurred while sending mail. The mail server responded: Must issue a STARTLS command first. For more information go to: https://support.google.com/a/answer/3221692 and review RFC 3207 specifications. 00721157ae682-765bb916a90sm38332507b3.4-gsmtp. Please verify that your email address is correct in your account settings and try again.***While I have looked at all of this, I can't really find a solution I know how to implement.***

I can send emails using Google webmail and when I do, the emails show up in my TB Sent items folder. I'm totally stumped and considering moving to Outlook. But TB has been perfect for me for years and I want to stay with it. Any help will be much appreciated!

Typically if I experience a security certificate exception, thunderbird will popup the certificate exception box, I click to get certificate and am done.

Today I cannot get the certificate popup to appear. which is fine I know where the certificates are managed but I have not a clue how to add a certificate OR what information to enter into the "Add security exception" dialogue box

Any help would be greatly appreciated.

My e-mail provider has done the annual update of security and provided a new e-mail cert; however, Thunderbird no longer successfully updates it.

Thunderbid gets to the point of confirming the security exception; however, does not proceed.

This is using ThunderBird 140.4.0esr (64-bit) from Ubuntu Snap, on Ubuntu LTS 24.04.3.

I regularly send/receive encrypted email on Windows with Outlook but seeing as most of my work is done on my Ubuntu partition, I was interested in a Linux solution. I was able to connect to my exchange server using owl automagically and see my email, no problem. I had some experience getting smart-card readers working on Ubuntu so I already had some things in place using the OpenSC Security Device. TB was able to talk to my card reader, grab the certificates, and I was able to set my S/MIME digital signing and encryption certificates. It definitely works, I can decrypt messages that I had already received in the way I expect, it checks if I have a card inserted, asks for me PIN, and the message decrypts correctly as I would expect. The issue is that if I try to send a signed email to myself, I get the error, "Sending of the message failed. You specified that this message should be digitally signed, but the application either failed to find the signing certificate specified in your Mail & Newsgroup Account Settings, or the certificate has expired." A similar message is sent if I try to encrypt (but not sign) a message to myself but for the encryption certificate.

I don't understand this message, as TB can definitely see my card, ask my card for my private key, and use it to decrypt messages, so I believe my E2E settings are correct. Neither certificate is expired, both expire sometime in 2027. I even added my companies root certificate to my Certificate Authorities in TB, so I don't believe it's an issue with my certificate being deemed invalid, and the error message certainly doesn't suggest as much. I've also tried both of my card-readers in case something was only looking at the first one, but both can be signed into correctly but neither let me send signed/encrypted email. The only clues I can see are the console error in my terminal when the message fails to send...

console.error: mailnews.send: "Sending failed; , exitCode=2147500037, originalMsgURI="

Also when I open a remote debugging session, this is the error shown...

mailnews.send: NS_ERROR_FAILURE: Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIMsgComposeSecure.beginCryptoEncapsulation]

   _startCryptoEncapsulation resource:///modules/MimeMessage.jsm:510
   _writePart resource:///modules/MimeMessage.jsm:558

Does anyone know what I might be doing wrong and nudge me in the correct direction?

Bonjour

Depuis quelques jours je rencontre le message suivant:

L’envoi du message a échoué. Une erreur est survenue lors de l’envoi de l’e-mail. Le serveur e-mail a répondu : 1jHjuyBzCXgNw StartTLS obligatoire. StartTLS mandatory.OFR303_199 [199]. Veuillez vérifier que votre adresse e-mail dans les paramètres du compte est correcte et essayer à nouveau.

Dans les paramètres du compte tout semble OK Merci pour votre aide Cordialement

I'm using Thunderbird 140.5.0esr. I have a remote email server on a small "linode" and recently had to restore it from a backup.

When opening Thunderbird, I get the message "The certificate for adonax.com expired on 10/29/2025." I've been getting emails up to and including yesterday.

I ran the renewal program (sudo certbot renew) from the command line of my remote server, and was told the certificate did not need renewing. The "expiry date" is shown to be 2026, March 20 when having certbot display the certificate information.

So, there is some sort of disconnect happening in the communications between Thunderbird and the locations of the certificates on my server. I'm hoping for some advice as to how to trace the path. One possibility is that there is a location on my server that is used to connect to the certs and this is holding stale information due to the recent restore done for the remote server. Another is that maybe there is cached information or something else blocking the request from Thunderbird.

From Thunderbird, I am presented with a form "Add Security Exception". This indicates that thunderbird is contacting the location adonax.com:993. I checked the port from the server using UFW and it is open to all. The Thunderbird form however hangs when I hit the "Get Certificate" button, and clicking the "Confirm Security Exception" appears to do nothing. The button "View..." opens a tab with the expired certificate. All the information on the certificate that is displayed by Thunderbird looks good, matches what I have in terms of URLs, but the dates are wrong.

Is there perhaps something blocking thunderbird from using port 993? Is there a way to test that? If 993 is working, I will try to research what is going on there at the Ubuntu end. I tried putting adonax.com:993 in Chrome and got an ERR_UNSAFE_PORT, for what that is worth.

Why do I suddenly (from one day to another) receive the message: "Das Zertifikat für imap.gmail.com stammt nicht von einer vertrauenswürdigen Quelle."

when trying to downlowd messages from Gmail?

I have not changed anything at all.

I generated a CSR file via the instructions at https://support.mozilla.org/en-US/kb/instructions-smime-certificate-using-csr#thunderbird:linux:tb145 . After submitting and receiving a certificate from a CA, importing it the People tab of the Certificate Manager does not do anything: nothing new appears in the Your Certificates tab.

Where are the private keys associated to the generated CSRs stored? How can I access them to resolve this?

Running 140.5.0esr via flatpak on Fedora 43 Kinoite.

Hello,

I am moving over to Thunderbird from outlook. I have about 8 emails with two domains. First email works okay. The second one on the same domain has turned red on the left panel and thunderbird keeps poppoing up the certificate for mail.xxx.com is not valid for the server. The other works I added the exception when setting it up. The mail server is another domain used from my cpanel hosting provider. So it does not match the domain of the emails.

I can't seem to find a way around this to get it to work. Also I under account settings it looks correct. I am thinking this error message is the incoming mail server? I don't see under account setting anything for incoming mail server which on my hosting is the same for incoming and outgoing. Appreciate any help.

Thank you!

Server Posteingang IMAP (empfohlen) imap.vodafonemail.de Ports für Posteingang IMAP SSL: 993 / TLS: 143

Server Postausgang SMTP smtp.vodafonemail.de Ports für Postausgang SSL: 465 / TLS: 25 oder 587

I have added my local CA to the Certificate Manager (CA.png). When I try to send, I get the "confirm security exception" message (CertError.png). Viewing the certificate gives the data in Server.png and CACert.png.

The server cert is properly signed: $ openssl verify -CAfile ca-chain.cert.pem Mercury2.i-pi.com587.cert.pem Mercury2.i-pi.com587.cert.pem: OK

Why am I getting the certificate error when the CA is loaded into Thunderbird?

OS: Ubuntu 24.04.2 LTS patched as of just now. Thunderbird: 128.10.2esr (64-bit) Thunderbird is installed by snap: $ sudo snap info thunderbird name: thunderbird summary: Mozilla Thunderbird email application publisher: Canonical✓ store-url: https://snapcraft.io/thunderbird contact: https://www.thunderbird.net/contact/ license: unset description: |

 Thunderbird is a free email application that’s easy to set up and customize
 - and it’s loaded with great features!

commands:

 - thunderbird

snap-id: k1Ml1O9GzSO2QftV0ZlWSbUfQ78nN460 tracking: latest/stable refresh-date: 3 days ago, at 10:48 MDT channels:

 latest/stable:    128.10.2esr-1 2025-05-23 (734) 220MB -
 latest/candidate: 128.11.0esr-1 2025-05-23 (735) 220MB -
 latest/beta:      139.0b4-2     2025-05-20 (731) 236MB -
 latest/edge:      ↑                                    

installed: 128.10.2esr-1 (734) 220MB -

I have spent some time digging through your messages about how to fix this issue. I get the general "where to" enable SSL/TLS but no trouble shooting to this specific level.

Spectrum (charter) Internet on May-30-25 a pop up "Add Security Exception" on wife's account (Image #1 below). We have same Internet provider and same server config's (except email name & password or course).

 This Security Exception has happened before, as well as on my account in the past. 

Although, I never got the Exception this time. We did "Confirm Security Exception" 2x on her account and she is up and running again. No issues.

  However, I can't receive e-mails with the Account Settings / Server Settings / Security Settings

"Connection Security" set to SSL/TLS" it must be set to "None" When set to SSL/TLS and I push the "Get Mail" button, the server isn't even banged as there's no msg in lower left frame of TB. I have gmail account and it does bang that one like it should. If set to "None" I get the msg in lower left TB frame showing connection to Charter server and I receive any outstanding e-mails. But I don't want to continue without a password.

 Under [Settings/ Privacy & security / Manage Certificates]

hers (Image #2 below) looks different than mine (Image #3 below). She has the 2 confirmed Security Exceptions, but also has a "View" and "Export" button that are bolded when the specific line item is highlighted. I do not have a View or Export button shown. How do I enable the SSL/TLS with password and actually receive emails?

 I am using TB 128.11.0esr (64-bit)

thx in advance Gene

Thunderbird 140.7.0esr allows me to e-mail my OpenPGP public key to myself, but it doesn't seem to have any way for me to get access to my private key. I was wondering how to export keys? Thanks!

I have 4 emails in Thunderbird, one of those I also have on my phone, it is receiving mail, on my desktop, two of the emails have no email today, and two I have only one email, all should have 10 to 20 or more emails. I do have the emails on the website, but they are not loading onto Thunderbird. I get this message, "The certificate for imap.knology.net is not valid for the server. Someone could be trying to impersonate the server and you should not continue.

 Can you offer any help?

I installed thunderbird on my new Samsung A26. I tried to configure the imap connection for my email - provider is liwest.at - per their settings. the incoming mail check worked. but the outgoing mail check gives back the error "unable to parse tls packet header" I checked username and password multiple times and tried all versions of password authentication possibilities.

I googled the error but the only thing I could find was a possible mismatch in tls versions. I asked my provider about it - their customer service could not confirm with their technicians what version is in use but according to their documentation it should be tls 1.2

Hello,

I have read this one https://support.mozilla.org/en-US/kb/openpgp-thunderbird-android-howto and I was aiming for additional detailed info on a specific step in the "Select an encryption key or create a new key" section.

From Thunderbird Desktop I can already send/receive encrypted emails from a specific email account and I have exported, on my laptop, my private and public keys as well as the public keys of some contacts.

On my Android phone I have Thunderbird for Android (version 14) already set up for the same email account and, in order to start using email encryption, I understood from the above link that I first need to install OpenKeychain and then, from the image in step 2 of "Select an encryption key or create a new key" and from the text of the subsequent step 3, that I'll need to choose "I already have a key. Import end-to-end key from other device" and then, if I got it right, try to find the keys which I exported on my laptop from Thunderbird Desktop.

Are there any precise details on how to find those exported keys and load them into OpenKeychain? Meaning, for instance, do I need to copy/paste the keys from my laptop into the archive of my Android phone and then direct Thunderbird/OpenKeychain to that location to pick them up?

Any type of details/links/docs/videos with respect to this, will be useful. As well as any explanations in case I understood wrongly and what I am trying to do is not the proper way to proceed.

Please note: I am not an expert.

Thank you

Best Regards